The Sept. 11 attack on the U.S. consulate in Benghazi was in fact "a terrorist attack" and the U.S. government has indications that members of al Qaeda were directly involved, a top Obama administration official said Wednesday morning.

"I would say yes, they were killed in the course of a terrorist attack on our embassy," Matt Olsen, the director of the National Counterterrorism Center, said Wednesday at a hearing of the Senate Homeland Security Committee, in response to questioning from Chairman Joe Lieberman (I-CT) about the attack that killed Ambassador Chris Stevens and three other Americans.

As for who was responsible, Olsen said it appears there were attackers from a number of different militant groups that operate in and around Benghazi, and said there are already signs of al Qaeda involvement.