A dozen people are reported to have been injured in an attack in the French city of Grenoble, in which one man is reported to have been beheaded.
A message in Arabic was reportedly found on the victim’s head, which had been pinned to a fence.
An Islamic State flag was reportedly found at the scene.
A man, who is said to be known to authorities, has been arrested at the scene of the attack in the Air Products facility, which sells gas canisters. Grenoble is located near the Alps in south-eastern France.
There are other reports of two attackers, each carrying Islamist flags, and another of one loud explosion.
Other sources said two men rammed the factory in a car before entering and setting off several small explosive devices and igniting gas canisters.
A French security official said the victim was found decapitated outside the entrance to the gas factory. Arabic writing was reportedly found on the head.
The official said two attackers arrived in a car, bearing banners written in Arabic, and set off an explosion.
French Interior Minister Bernard Cazeneuve said he would go “immediately” to the scene, his office said.
Local journalist Stefan de Vries said the head of the man who was decapitated was found yards from his body.
The arrested man reportedly said he was a member of Islamic State.