Obama: Extremists used video as 'excuse' to attack

 President Barack Obama says extremists used an anti-Islam video as an excuse to assault U.S. interests, including an attack on the U.S. consulate in Libya that left four Americans dead.

Speaking at a candidate forum on Spanish-language network Univision, Obama said the attack that killed Ambassador Chris Stevens and three other Americans is under investigation.

Asked if the attack was by al-Qaida, Obama said, "We don't know yet."Obama said the U.S. has insisted on and received cooperation from governments in Egypt, Libya, Tunisia and other countries as it investigates the attack. 

He said groups affiliated with al-Qaida "have not gone away" and remain dangerous.

Earlier Thursday, White House spokesman Jay Carney called the incident in Libya a "terrorist attack." Obama himself did not use that phrase.