"Based on what we know right now it does seem that's what we're confronting here. And this is an act of violence that we certainly do condemn, and if based on this investigation it turns out to be an act of terrorism, then we would condemn that in the strongest possible terms, too," said [White House press secretary Josh] Earnest.
Heavily armed gunmen shouting Islamist slogans stormed a Paris satirical newspaper office Wednesday and shot dead at least 12 people in the deadliest attack in France in four decades.
Police launched a massive manhunt for the masked attackers who reportedly hijacked a car and sped off, running over a pedestrian and shooting at officers.
Police said witnesses heard the attackers, who were armed with a Kalashnikov and rocket launcher, shout "we have avenged the prophet" and "Allahu akbar" (God is greatest).
Two police were confirmed among the dead and four people were critically injured.
The capital was placed under the highest alert status after the attack on Charlie Hebdo, a satirical weekly that has sparked anger in the past among Muslims for publishing cartoons of the prophet Mohamed.