On Wednesday afternoon, a 21-year-old woman from Reims accompanied by two females friends was relaxing in a bathing costume in the Léo-Lagrange park. Five young girls from various districts of the city were passing close by. One of them broke away from the group. Seeing this woman sunbathing, stretched out on the grass, seemed contrary to her ideal of morality and her conception of proper conduct because she came to rebuke her for her light clothing which she considered indecent in such a place.
Frightened by this kind of language with its airs of a religious police, she replied saying it was not for her to dictate how she should dress. An altercation broke out. All of the group then rushed in on her to rain blows upon her. Witnesses gave aid to the victim and alerted the fire brigade who had to take her to the university hospital.Source
UPDATE: The girl involved in the incident has admitted she is a Muslim but claims she is "tolerant" and wasn't motivated by religious considerations. This is apparently a video of the aftermath of the incident.