Violent scenes mired England’s first match of the Euro 2016 tournament with clashes between fans and police inside the stadium and on the streets.
England drew 1-1 with Russia inside Marseille’s Stade Velodrome, but before the final whistle sounded trouble was brewing.
The closing minutes of the match saw three flares set off inside the stadium.
A white flare was lit from seating at the Russia end, before a green rocket soared over the England goal, defended by Joe Hart.
This was followed by a bang and a second red firework, visibly alarming the players.
Questions have been raised over security after the fireworks were allowed into the stadium, at a time when France is on high alert from a terror attack.
Those in the stands described a “dangerous stampede” as the 67,000 capacity stadium descended into chaos as fans began fighting each other after the full-time whistle.
Dan Roan, a sports editor at the game, tweeted: “The rush of fans behind goal. See bottom-right of stand, England supporters jumping over perimeter fence in panic
“Big q's for UEFA here; stampede appears to have been triggered by explosion. How did such a device make it inside and where was segregation?"
Another England fan, Adam Turk, tweeted: “Have never had to run out of a stadium before. Scariest experience of my life.”
French officials face further criticisms of no police being on hand to quell the violence, only stewards in hi-vis.
England fan Dr Aidan Elliot tweeted: “Having been caught in the middle of this in the stadium, there NO police at all: this was a dereliction of duty.”
Fans are said to have been able to easily tear down the flimsy segregation, made of only blue tarpaulin, to attack rivals.
Russian supporters clad in balaclavas are said to have broken through barricades and stewards launching an all-out assault on England fans.
Photos from inside the stadium show fans fleeing in panic while other traded blows with one another, with reports fans who could not get out fast enough beaten and kicked.
England fans desperately tried to climb over fences and seating to escape the onslaught of the hard-line Russians.
Women and children are thought to have been caught in the panic as fans tried to leave the stadium en masse.
Rebekah Vardy, Jamie Vardy’s new wife, tweeted: “That has to be up there with the worst experience ever at an away game! Teargassed for no reason, caged and treated like animals.”
FA spokesman Mark Whittle condemned the day’s event at a post-match conference.
He said: "The FA is very disappointed about the terrible scenes of disorder and of course condemns such behaviour.
"It is now in the hands of the relevant authorities to identify those involved in trouble and deal with them appropriately and quickly.
"At this time the FA urges England supporters to act in a respectful manner and support England in the right way."
England coach Roy Hodgson refused to comment in detail on the incidents, but said the players "weren't particularly aware (of what happened) and it certainly had no effect on our preparation for the game and our performance in the game."
Russia faces a Uefa investigation after the shocking conduct of their fans in the stands which marks some of the worst football violence in recent years.
Before the match began there were violent and chaotic scenes in the French port town for the third day in a row.
According to reports 31 people were injured in clashes, with four seriously hurt and two men left fighting for their life.
A 51-year-old man is said to have suffered a cardiac arrest, with police performing CPR on the unnamed England fan.
He was later taken to Marseille hospital in a critical condition.
Police spokesman Matthieu Duroselle, said: “There is one English fan that has been badly injured.
“His heart stopped but it was restarted by a police officer who provided heart massage at the scene.”
A second man was allegedly set upon by Russian “ultras” and repeatedly beaten over the head with a metal pole.
A third man, 48-year-old John Burrow, is said to have been slashed by a knife-wielding Russian, according to the Mirror.
The paper reported he needed six stitches to a head wound after being sliced by a rival fan.
His friend, Tony Daniels, 47, from Nottingham, said: “There was blood everywhere. They attacked him with a knife or hatchet.
“We were sat in the harbour, drinking, and some of the young lads started giving it some banter.
“All of a sudden the Russians charged down the road like an army. It was terrifying.
“We dived into a bar and they pulled the shutters down, but John got stuck outside and they wouldn’t let him in.
“We spotted him later being looked after by some other people. He was covered in blood. He said he’d been slashed by the Russians.”
At least 20 England fans are thought to have been injured.
Three police officers are said to have been hurt and six arrests were made.
Julian King, British ambassador to France, tweeted: "Number of Brits in hospital overnight. Consular following closely with French authorities."
Outside the stadium, French police used a water cannon and tear gas on fans, reportedly English, Russian and French.
Behaviour of the Three Lions supporters has been heavily criticised, with reports that boozed up Brits were throwing bottles, chairs and other missiles and police and rivals.
The latest round of violence has seen marauding packs of Russian “ultras” making a beeline for the England fans, resulting in shocking scenes unfolding around the town, particularly in the square.
Photos show scores of bloodied fans being helped by friends and emergency services as pockets of fighting continues down side streets and alleyways.
Police are said to have ordered the bars and pubs to shut after the match to stop further fighting.
A Foreign Office spokeswoman said: "We are in contact with French authorities about a British national injured in Marseille and stand ready to provide further support."
Britons in France who need consular support can contact the embassy 24 hours a day on +33 1 4451 3100.
England’s next match is against Wales on Tuesday.
