Footage shot by anti-bullfighting campaigners supposedly shows clashes between them and those who support the spectacle in a town in the southwest of France.
Eight people were hurt after violence broke out at an arena in Rion-des-Landes on Saturday.
Some anti-bullfighting campaigners say they were assaulted by police.
Anti-bullfighting activist Jean-Pierre Garrigues described the condition of a fellow protester, aged 60, who was airlifted to hospital and put in a medically-induced coma. The injured man will be filing a complaint against the owners of the arena, according to Garrigues.
Bullfights take place in the southwest of France during the summer but are controversial.
Last September, France’s Constitutional Court refused to ban the spectacles or classify them animal cruelty. However, they are banned in some parts of the country.
The Spanish region of Catalonia banned bullfighting in 2012.