Heathrow Terminal 4 has reopened three hours after it was evacuated when firefighters rushed to what was described as a “possible hazardous materials incident”.
Some 21 people reported an injury at Heathrow Airport but no trace of any “adverse” substance was found, the Metropolitan Police said.
Dozens of flights were delayed, hitting thousands of travellers. Many flights were operating up to two hours late, but a flight to Spain was scheduled to be three hours late.
Crowds gathered outside the terminal and staff handed out foil blankets to passengers as temperatures began to fall. Witnesses said they were confused as “no one really knew what was going on”.
Heathrow bosses allowed passengers back into the terminal at 8pm after about three hours.
The Met Police said: "Specialist officers attended the scene alongside the London Fire Brigade and London Ambulance Service and conducted a thorough search of the area. No trace of any adverse substance was found.
"Around 20 people reported an injury. None were deemed to be life-threatening or life-changing. Enquiries are ongoing."
Key Points
- Terminal 4 safe to reopen as Heathrow stands down incident
- Flights still scheduled to depart on time, airport says
- National Rail says trains unable to call at Terminal 4
- Firefighters responding to 'possible hazardous materials incident' at airport
- Heathrow Terminal 4 closed and evacuated
Heathrow apologises for disruption
23:00 , Bryony GoochHeathrow Airport has apologised for disruption as it reopens Terminal 4.
“We are very sorry for the disruption caused, the safety and security of our passengers and colleagues is our number one priority.
“We encourage passengers to check with their airline for the latest information about their flight this evening and our colleagues will be on hand into the night to assist.”
How busy is Heathrow Airport?
22:31 , Bryony GoochLondon Heathrow is the UK’s busiest airport, and just last month it recorded its busiest day ever.
The airport saw more than a quarter of a million passengers passing through its four terminals - a total of 270,869 passengers - on 1 August.
It came after a month in which it saw almost no growth in passenger numbers, which executives said was due to capacity constraints.
The UK’s busiest airport said that 7,981,137 passengers flew in and out of the terminals in July.
That is compared with 7,980,455 during July 2024.
Terminal 4 disruption intensifies with departures in jeopardy
22:15 , Bryony GoochDelays for flights hit by the emergency evacuation of London Heathrow Terminal 4 are increasing.
An airport spokesperson said: “We are doing everything we can to ensure all flights depart as planned today.” But they are certainly not keeping to schedule.
According to Flightradar24 data analysed by The Independent, Qatar Airways has yet to dispatch any of the three flights from Heathrow to its hub in Doha – they are running two or three hours behind schedule.
The same degree of delay is affecting two Etihad flights to Abu Dhabi, which will jeopardise hundreds of connections.
For longer flights to east Asia, it looks increasingly likely that some departures may be delayed overnight if the crew run “out of hours” – and are unable to operate the flight within their legally permitted shifts.
The Korean Airlines departure to Seoul, due out at 7.35pm, is currently running three hours late – and with a flight time of around 12 hours to the Korean capital, if the delay increases the flight could be jeopardised.
Recap: Terminal 4 reopened and deemed safe
22:00 , Bryony GoochThe incident which closed Heathrow terminal 4 has been stood down, with emergency services confirming the terminal is safe to reopen.
A Heathrow spokesperson said: “Emergency services have confirmed Terminal 4 is safe to reopen and we are doing everything we can to ensure all flights to depart as planned today.
“We are very sorry for the disruption caused, the safety and security of our passengers and colleagues is our number one priority.
“We encourage passengers to check with their airline for the latest information about their flight this evening and our colleagues will be on hand into the night to assist.”
In pictures: Scenes from outside Terminal 4 during the evacuation
21:32 , Bryony Gooch
Event suspected to be 'mass hysteria'
21:23 , Jane DaltonA police source said what happened at Heathrow Airport as a "mass hysteria" type event.
The source told the BBC an incident may have "snowballed".
No dangerous substance was found.
Ambulance crews treat 21 people
21:16 , Jane DaltonA London Ambulance Service spokesperson said a total of 21 patients had been treated, and one had been taken to hospital.
All the others were discharged at the scene.
No trace of 'adverse' substance found, say police
20:55 , Jane DaltonAround 20 people “reported an injury” and no trace of any “adverse substance” was found after officers were called to Heathrow, the Metropolitan Police say.
A spokesperson said: "On Monday, September 8 at 16:56hrs police were called to a potential hazardous materials incident at Heathrow Airport, Terminal Four.
"Specialist officers attended the scene alongside the London Fire Brigade and London Ambulance Service and conducted a thorough search of the area.
"No trace of any adverse substance was found.
"Around 20 people reported an injury. None were deemed to be life-threatening or life-changing.
"Enquiries are ongoing."
Around 20 people assessed by paramedics
20:50 , Bryony GoochAround 20 people have been assessed on scene by paramedics from the London Ambulance Service, London Fire Brigade has said.
The cause of the incident remains under investigation at this time.
Emergency services declare terminal safe
20:42 , Jane DaltonEmergency services say Heathrow's Terminal 4 is safe to reopen, according to airport chiefs.
In a social-media post, the airport said: "Emergency services have confirmed Terminal 4 is safe to reopen and we are doing everything we can to ensure all flights to depart as planned today.
"We are very sorry for the disruption caused, the safety and security of our passengers and colleagues is our number one priority.
"We encourage passengers to check with their airline for the latest information about their flight this evening and our colleagues will be on hand into the night to assist."
What we don't know about the Heathrow incident
20:40 , Bryony GoochAs Terminal 4 reopens, here are the questions that remain about its evacuation:
- What caused the evacuation over a ‘possible hazardous materials incident’?
- How many people were affected - and in what way?
- Will it have an ongoing impact on travel from the terminal this evening?
More than 12 flights severely delayed
20:31 , Jane DaltonThousands of passengers have been affected by the shutdown of Heathrow Terminal 4, with more than a dozen flights severely delayed, writes Simon Calder.
The leading airline at Terminal 4, Qatar Airways, has three departures to Doha that are running about two hours behind schedule.
The delays will mean that many passengers will miss their connections at the airline’s hub.
A Vueling flight to Santiago de Compostela is currently three hours adrift.
Many other flights are operating between 90 minutes and two hours late, including Royal Air Maroc to Casablanca and Air Algerie to Algiers.
Among later departures, the average delay is an hour. They include China Southern to Beijing, Malaysia Airlines to Kuala Lumpur and El Al to Tel Aviv. The last of these is predicted to depart at 11.30pm, well after the normal shutdown of operations for the night.
Travel correspondent Simon Calder has background on Terminal 4
20:30 , Bryony GoochTerminal 4 was a 1980s stopgap while waiting for the longest planning inquiry in history, for Terminal 5, to conclude. Despite a refurbishment it remains largely unloved by passengers and airlines.
T4 is in the wrong place (aircraft using the northern runway have to taxi across the active southern runway), and transport links to the rest of the airport and beyond are poor compared with the other terminals.
The major airlines that use it are mainly Middle Eastern and east Asian. By far the most important carrier is Qatar Airways, with eight flights a day to and from its hub in Doha. Etihad, Gulf Air, Oman Air, Saudia and Israel’s El Al are the other Middle Eastern representatives.
To Asia, China Southern and China Eastern have busy schedules to the People’s Republic. Vietnam Airlines flies to Hanoi and Ho Chi Minh City. Korean Airlines to Seoul and Malaysia Airlines to Kuala Lumpur are major network carriers.
Short haul flights comprise a mix of members of the Skyteam alliance, including Air France and KLM, as well as airlines with no obvious loyalties elsewhere, such as Air Malta and Bulgaria Air. Air Algerie and Royal Air Maroc serve Algiers and Casablanca respectively.
Transport minister monitoring Heathrow situation
20:20 , Bryony GoochTransport minister Heidi Alexander has said she is monitoring updates after Heathrow Terminal 4 was evacuated earlier this evening.
“Emergency services are responding to an incident at Heathrow’s Terminal 4 which has prompted its evacuation. I’m monitoring updates from those on the scene, as well as Heathrow Airport itself.
“Passengers should not travel to Terminal 4 until advised otherwise.”
Emergency services are responding to an incident at Heathrow’s Terminal 4 which has prompted its evacuation.
— Heidi Alexander MP (@Heidi_Labour) September 8, 2025
I’m monitoring updates from those on the scene, as well as Heathrow Airport itself.
Passengers should not travel to Terminal 4 until advised otherwise.
In pictures: Airport staff hand out foil blankets to evacuated travellers
20:10 , Bryony Gooch
Breaking: Terminal 4 safe to reopen as Heathrow stands down incident
20:07 , Bryony GoochThe incident which closed Heathrow terminal 4 has been stood down, with emergency services confirming the terminal is safe to reopen.
A Heathrow spokesperson said: “Emergency services have confirmed Terminal 4 is safe to reopen and we are doing everything we can to ensure all flights to depart as planned today.
“We are very sorry for the disruption caused, the safety and security of our passengers and colleagues is our number one priority.
“We encourage passengers to check with their airline for the latest information about their flight this evening and our colleagues will be on hand into the night to assist.”
Travellers ushered 150m from Terminal 4 in evacuation - reports
20:00 , Bryony GoochPassengers were ushered about 150 metres away from Terminal 4 in the evacuation, eyewitness Paul Scott has told Sky News.
Mr Scott told the broadcaster he had just checked in and was about to go through security when the evacuation happened.
He said everyone who was in the departure hall had been evacuated and passengers were ushered away to about 150 metres from the terminal building, adding privacy screens had been put up and a number of people in white suits arrived at the scene.
Mr Scott added the mood was fine but it was a little confusing as no-one really knew what was going on.
Mr Scott, who was planning to fly to Sri Lanka on business as part of a group of six, told Sky News that people have been handing out silver blankets as the temperature was dropping.
Train services to Heathrow were already disrupted because of London Underground strike
19:43 , Bryony GoochNational Rail issued a statement saying that trains were unable to call at Heathrow Terminal 4 due to an incident, although services to the airport were already disrupted due to the London Underground strikes.
Heathrow said on Sunday: “London Underground strike action between Sunday 7 September until Friday 12 September - tube services will be severely disrupted, with little to no service expected.“Heathrow Express, Elizabeth Line and bus services are running as normal. Please plan your journey carefully before travelling to the airport.”
London Underground strike action between Sunday 7 September until Friday 12 September - tube services will be severely disrupted, with little to no service expected.
— Heathrow Airport (@HeathrowAirport) September 7, 2025
Heathrow Express, Elizabeth Line and bus services are running as normal. Please plan your journey carefully before… pic.twitter.com/PXirhLogyl
In pictures: Emergency services respond to 'possible hazardous materials incident'
19:39 , Bryony Gooch
How busy is Heathrow Airport?
19:36 , Bryony GoochLondon Heathrow is the UK’s busiest airport, and just last month it recorded its busiest day ever.
The airport saw more than a quarter of a million passengers passing through its four terminals - a total of 270,869 passengers - on 1 August.
It came after a month in which it saw almost no growth in passenger numbers, which executives said was due to capacity constraints.
The UK’s busiest airport said that 7,981,137 passengers flew in and out of the terminals in July.
That is compared with 7,980,455 during July 2024.
Flights still scheduled to depart on time, according to Heathrow airport
19:32 , Bryony GoochAccording to Heathrow airport’s website, flights from the affected terminal are still scheduled to depart on time, with only one delay to a Saudia airline flight to Jeddah in Saudi Arabia currently expected.
Trains unable to call at Terminal 4 amid 'possible hazardous materials incident'
19:30 , Bryony GoochNational Rail has issued a statement saying that “trains are unable to call at Heathrow Terminal 4 due to the emergency services dealing with an incident”.
⚠️INFO: #HeathrowTerminal4 - Trains are unable to call at Heathrow Terminal 4 due to the emergency services dealing with an incident
— National Rail (@nationalrailenq) September 8, 2025
All other terminals operating as normal, Heathrow says
19:25 , Bryony GoochAll other terminals are operating as normal, Heathrow airport has said as terminal 4 has been closed and evacuated while emergency services respond to an incident.
London Fire Brigade has said specialist crews have been deployed to carry out an assessment of the scene and the terminal has been evacuated as a precaution.
In pictures : Terminal 4 evacuated as emergency services respond to incident
19:18 , Bryony Gooch
Watch: Heathrow Airport terminal evacuated as emergency services respond to ongoing incident
19:13 , Bryony GoochFirefighters responding to 'possible hazardous materials incident' at Heathrow
19:08 , Bryony GoochA London Fire Brigade spokesperson has told The Independent: "Firefighters are responding to a possible hazardous materials incident at Heathrow Airport.
"Specialist crews have been deployed to carry out an assessment of the scene, and Terminal 4 has been evacuated as a precaution whilst firefighters respond.
"The Brigade was first called about the incident at 1701, and crews from Feltham, Heathrow, Wembley and surrounding fire stations have been sent to the scene."
'Please do not travel to Terminal 4' says Heathrow, as colleagues are supporting passengers on site
18:59 , Bryony GoochHeathrow Airport released the following statement on X: “Terminal 4 check-in has been closed and evacuated while emergency services respond to an incident.
“Please do not travel to Terminal 4, colleagues are supporting passengers on site. We will provide further information as soon as we can, all other terminals are operating as normal.”
Heathrow Terminal 4 closed and evacuated
18:58 , Bryony GoochHeathrow terminal 4 has closed and evacuated its check-in, according to a statement from the airport.
We will keep you updated as this incident unfolds this evening.
