From BBC news:
"Chris Slegg, a BBC London reporter on holiday in Marseille for the football, said he had been at a bar with friends and other fans on Friday night, watching France's game against Romania, and the atmosphere had been friendly.
However, shortly after the match finished, a group of 20 to 30 French youths had emerged from side streets and thrown firecrackers and bottles at people who had been watching the game outside the bar, he said. The incident had been completely unprovoked, he said."