Hollande, who was rushing back to France from an EU summit to deal with the crisis, 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.”
The killing came nearly six months after the Islamist attacks in and around Paris that killed 17 people in January, starting with a shooting at satirical magazine Charlie Hebdo.