A man has been arrested in connection with the deaths of 39 people.
The bodies were found inside a lorry container in Essex, it is being reported on Wednesday morning.
Emergency services were called to Waterglade Industrial Park at Eastern Avenue in Grays at around 1.40am on Wednesday.
It is understood the 39 people were pronounced dead at the scene. Early reports suggest 38 there are adults and one aged in their teens, Belfast Live reports.
A 25-year-old-man from Northern Ireland has been arrested on suspicion of murder.
Chief Superintendent Andrew Mariner said: “This is a tragic incident where a large number of people have lost their lives. Our enquiries are ongoing to establish what has happened.
“We are in the process of identifying the victims, however I anticipate that this could be a lengthy process.
“We believe the lorry is from Bulgaria and entered the country at Holyhead on Saturday 19 October and we are working closely with our partners to investigate.
“We have arrested the lorry driver in connection with the incident who remains in police custody as our enquiries continue. I appreciate this cordon is going to disrupt the activity of local businesses in the area and we will work to ensure that disruption is kept as short as possible.
“We are working with Thurrock Council to mitigate against any impact our investigation scene will have locally.”
A cordon has been put in place and access to and from the Waterglade Industrial Park remains closed.
Paige Wade was driving past the industrial park at 4.15am on the way home from work.
She told the PA news agency: "I honestly didn't see much, I had just finished work while driving up Motherwell Way and all you could see was blue flashing lights, as I was driving past there was police tape to cordon off the start of eastern avenue.
"I knew it was serious because of how many police cars and ambulances were there, but the police had parked their cars across the whole access of the road so you couldn't see anything.
"There's always lorries around there as they park up there for the night, I couldn't say whether I did or didn't see the actual lorry in question."
A cordon has been put in place and access to and from the Waterglade Industrial Park remains closed.
Nine police cars and fifteen police officers have been stationed at the scene, which is close to the shopping location Lakeside.
A statement regarding the discovery will be delivered by DCC Pippa Mills at Grays Police Station at 11.30am this morning.
Ferries sail out of Holyhead port to Dublin in Ireland.
It is the principal link for road vehicles to get from England and Wales to Ireland.
More than two million people travel through the port each year, which is operated by Stena Line Ports Ltd.
Back in June 2000 the bodies of 58 Chinese immigrants were found in a lorry in Dover.
A Dutch driver was jailed the following year over their manslaughter.
