A shooting occurred in the Planoise district of Besançon. Around thirty shots were heard by local residents, according to L'Est Républicain.
According to the outlet, several men shot others in the middle of the night using automatic weapons. The emergency services reported at least three injured, one of them was in grave condition.
"I thought people were celebrating Christmas with firecrackers," said a local resident.
The attackers reportedly opened fire on Rue de Friborg, according to initial information. The neighbourhood is now completely closed.
Teams of technicians and deminers were dispatched to the site. There is also a heavy police presence at the scene and surrounding streets.
Local residents claimed to have observed a man throwing a grenade, the outlet reported. A motive for the shooting has not yet been determined.