The Nice public prosecutor on Tuesday announced the opening of an investigation into aggravated assault after a confrontation between Nice football club and their own supporters.
Nearly 200 Nice ultras gathered outside the team's training centre on Sunday to vent their anger at the players and coaching staff after a 3-1 defeat at Lorient in Ligue 1 earlier in the day.
Two players subsequently lodged complaints with the police. Witnesses said Terem Moffi and Jeremie Boga were on the receiving end of much of the fans' ire, although neither was named by the prosecution.
The players told officers that when they arrived at the training centre on their return from the airport, the team bus was blocked by supporters "in a tense atmosphere", according to the statement made by Nice public prosecutor Damien Martinelli.
They had to get off the bus and walk the short distance to the training centre through the crowd of angry supporters. They said they were "punched, kicked and spat on while being insulted".
Many of the supporters had their faces covered, added the public prosecutor's office.
The investigation into "aggravated assault, participation in a group preparing violence or damage to property, and failure to prevent a crime against physical integrity" has been handed to the criminal police and "numerous interviews" were underway.
According to the prefecture, around 20 police were in place outside the training centre after the club warned that fans were preparing a hostile reception.
The decision was made not to clear the area before the bus arrived so as not to exacerbate the situation.
When the players had to get off the bus, police saw a scuffle and the setting-off of smoke bombs, said the prefecture.
They did not observe any violence or attempted blows, although some may have gone unnoticed in the confusion.
The French football league (LFP) announced on Tuesday that it would be joining the players as a plaintiff "in order to fully support their action and help shed light on these tense events".