An attacker carrying an Islamist flag reportedly set off explosives and decapitated someone at a factory in France

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Unknown persons rammed a car into the premises of a US gas company in southeast France on Friday, exploding gas containers in an apparent attack which bore the hallmarks of Islamist militants and left one dead and several wounded, police sources and French media said.

The factory, called Air Products, is in Saint-Quentin-Fallavier near Grenoble.

A severed head with Arabic writing was found pinned to the gates of the factory and a decapitated body was found in the factory, according to AFP.

One person has been arrested, according to the Associated Press. There might have been a second attacker - a source told the AP that two attackers arrived at the factory by a car bearing banners with Arabic writing.

The motive for the attack is so far unclear.

A source told AFP that the attacker is believed to have set off several small explosive devices in the factory.

The suspect is reportedly a 30-year-old man who was known to intelligence agencies, according to French media.

French authorities have reportedly opened a terrorism investigation into the attack.

Sources have claimed the flag had Islamic State inscriptions, but it's unclear whether the attacker was affiliated with any one terror group.

#France: #IS tweep claims "IS flag" at #Grenoble attack scene. Even if true, this doesn't mean it was planned by IS. pic.twitter.com/G8611wL5uG

- Charlie Winter (@charliewinter) June 26, 2015

This would be the second major such incident in France this year, coming after Islamist gunmen killed 17 people in January in attacks on the offices of the Charlie Hebdo satirical weekly and a Jewish food store.

Screenshot / Sky News

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