A French prosecutor says four people are in custody in an investigation into a beheading and an explosion at a U.S.-owned gas factory in southeastern France Friday. Police are still searching buildings for evidence.



Paris Prosecutor Francois Molins said the attacker was known to factory personnel because he came in regularly for deliveries. The attacker entered the factory grounds in a utility truck, then crashed the vehicle into a hangar at the site, prompting an explosion.



Molins says a knife and a decapitated body were found near the crashed truck and the body's head was found hanging on a gate. The head was surrounded by two flags carrying Islamic declarations.



Molins said the attacker, his wife, sister and another suspect are in custody. He said investigators are trying to determine whether there are accomplices. 

Terror attacks also happened in Kuwait and Tunisia. The White House released a statement condemning all three attacks. White House Press Secretary Josh Earnest said in part, "our thoughts and prayers are with the victims of these heinous attacks, their loved ones, and the people of all three countries."

The U.S. Embassy in Paris is warning American citizens to be vigilant. It released a statement urging Americans to report suspicious activities and stay away from any security incidents.



It also noted that French authorities have increased the terrorism alert level in recent months since attacks in January in Paris left 17 victims and three Islamic attackers dead, so there are more troops and police in the streets than in previous years.