At least one assailant rammed a car onto the premises of a U.S. gas company in Saint-Quentin-Fallavier, southeast France, June 26, 2015, causing oxygen containers to explode. One person was found decapitated and two others were injured.

Here, French special police forces escort a woman from a residential building during a raid in Saint-Priest, near Lyon, France, June 26, 2015. The suspect arrested in connection with an Islamist attack did not have a criminal record but had been under watch as being possibly radicalized, according to Interior Minister Bernard Cazeneuve, June 26, 2015.

French special police forces stand guard in front of a residential building during a raid in Saint-Priest, near Lyon, France, June 26, 2015.

Spain's Interior minister Jorge Fernandez Diaz (2nd L) speaks with Socialist party representatives Patxi Lopez (3rd R) and Antonio Hernando (2nd R) and Jose Enrique Serrano (R)during an urgency meeting at the interior ministry in Madrid, June 26, 2015. European leaders condemned the "heinous" suspected Islamist attack on a gas factory in France and massacres in Tunisia and Kuwait, vowing to stay united against "barbarism".

One person was decapitated near Lyon in southwestern France while in Tunisia gunmen killed at least 27 people in a beach resort and in Kuwait a suicide bombing at a mosque killed 13.

The Air Products gas factory in Saint-Quentin-Fallavier, near Lyon, southeastern France, after an assault June 26, 2015, in which a decapitated head was pinned to the gates.

One person was killed and several others were injured.

French police secure the entrance of the Air Products company in Saint-Quentin-Fallavier, near Lyon, June 26, 2015.

French Gendarmes stand guard next to a black plastic sheet outside a gas company site at the industrial area of Saint-Quentin-Fallavier, near Lyon, France, June 26, 2015.

One of the attackers reportedly waved an Islamic State of Iraq and Syria flag.

French security and emergency services gather at the entrance of the Air Products company in Saint-Quentin-Fallavier, near Lyon, southeastern France, June 26, 2015.

A general view shows the Air Products gas factory site at the industrial area of Saint-Quentin-Fallavier, near Lyon, France, June 26, 2015. A decapitated head covered in Arabic writing was found at a a site belonged to Air Products, a U.S.-based industrial gases technology company, in southeast France on Friday, police sources and French media said, after two assailants rammed a car into the premises, exploding gas containers. REUTERS/Emmanuel Foudrot - RTX1HWWH

A French Gendarme blocks the access road to the Saint-Quentin-Fallavier industrial area, near Lyon, France, June 26, 2015.

French Interior Minister Bernard Cazeneuve gives a press conference near the entrance of the Air Products gas factory in Saint-Quentin-Fallavier near Lyon, southeastern France, June 26, 2015.

A suspect arrested in connection with the attack on a French gas factory was investigated nine years ago for radicalization and has links to the Salafist movement, Cazeneuve said.

A French Gendarme blocks the access road to the Saint-Quentin-Fallavier industrial area, near Lyon, France, June 26, 2015.