An attacker carrying an extremist flag killed one person and injured several others Friday at a gas factory in eastern France, according to a legal source.

An attacker carrying an extremist flag killed one person and injured several others Friday at a gas factory in eastern France, according to a legal source.

The suspected attacker entered the factory and set off several small explosive devices, the source said. A decapitated body was found nearby the factory, another source said.

"According to the initial findings of the enquiry, one or several individuals on board a vehicle, drove into the factory. An explosion then took place," said one of the sources.

"The decapitated body of a person was found nearby the factory but we do not yet know whether the body was transported to the place or not," added this source, adding that a "flag with Arabic writing on it was found on the scene."

President Francois Hollande, who was rushing back to France from an EU summit to deal with the crisis, said the attack was a "terrorist " one.

He added that the person who launched the attack has been identified and that there may have been a second attacker.

"This attack was in a vehicle driven by one person, perhaps accompanied by another, which rammed its way at high speed into this establishment which contained bottles of gas," Hollande told a hastily-convened news conference.

"The intent was without doubt to cause an explosion. It was a terrorist attack."