A 16-year-old English fan has been charged with violence and a 50-year-old man is in hospital with severe brain injuries following three days of fighting in Marseille that involved 150 "hyper rapid, hyper violent" Russian hooligans.
French prosecutors said the teenager had been charged with throwing bottles during the chaotic scenes. Five other Britons are also due in court charged with offences.
But despite the behaviour of the Russian fans - they fought running battles in the streets and also charged at England fans in the Stade Velodrome after Saturday night's 1-1 opening draw - no Russians have been arrested over the violence.
As a result, England manager Roy Hodgson and captain Wayne Rooney have appealed directly to fans to "stay out of trouble" following Uefa's threat to expel the team from Euro 2016.
In an unprecedented move, the pair recorded a video, shared by the Football Association on Twitter. Hodgson and Rooney urge supporters to do everything in their power to avoid repeats of the violent scenes which marred their time in Marseille.
-- England (@England) June 13, 2016
Hodgson pleaded with fans to ensure Uefa's threats to dismiss England and Russia from the tournament should there be further disturbances "are never carried out". Rooney asked those without tickets for games not to travel.
Brice Robin, chief Marseille prosecutor, told reporters the British teenager was in custody and that he had personally spoken to Uefa to get his future tickets cancelled.
He said about 150 Russian hooligans had been involved in the trouble, describing them as "hyper violent" and "hyper rapid".
But he said just two Russian fans had been arrested, both for a pitch invasion.
And he said 50-year-old Portsmouth supporter Andre Bache, known as Pepe, was in a critical condition in a French hospital after being beaten round the head by Russians armed with iron bars.
He said officials had been unable to stop the Russian thugs as they had arrived in the city by train.
Uefa branded the behaviour of both England and Russia fans before and after their 1-1 draw "unacceptable". They said it would not hesitate to impose additional sanctions.
The tournament organiser also opened disciplinary proceedings against the Russian Football Union for alleged crowd disturbances, racist behaviour and the setting-off of fireworks by its fans during the game on Saturday night.
Meanwhile, a Northern Ireland football fan died after a fall in Nice following the team's 1-0 defeat by Poland.
Darren Rodgers, 25, from Ballymena, Co Antrim, toppled 26ft (8m) over a barrier from a promenade on to a hard pebble beach in the south coast city at around 2am on Monday, police said.
Asked whether David Cameron was concerned that England could be expelled from Euro 2016 over hooliganism, the Prime Minister's official spokeswoman said: "The Government is deeply concerned by the violence in Marseille at the weekend, including the reports of fans being attacked by rival supporters.
"We welcome Uefa's decision to launch an investigation into the violence and we will look at how we can support that while engaging with our European partners."
On the question of whether England or Russia might be disqualified if there is further violence, she said: "That's a matter for Uefa and for them to judge. They need to make judgments based on what is happening on the ground."