Attacker pledged allegiance to ISIS

Investigators think that as the San Bernardino, California, massacre was happening, female shooter Tashfeen Malik posted a pledge of allegiance to ISIS leader Abu Bakr al-Baghdadi on Facebook, three U.S. officials familiar with the investigation told CNN.

Malik's post was made on an account with a different name, one U.S. official said. The officials did not explain how they knew Malik made the post.

A law enforcement official said it appeared that Wednesday's mass shooting -- which left 14 people dead and 21 wounded before the two attackers, Malik and her husband, Syed Rizwan Farook, were killed in a shootout with police -- may have been inspired by ISIS. 

But none of the officials said that ISIS directed or ordered the attack. ISIS has called for people worldwide to launch attacks in its name, but isn't known to have claimed credit for what happened in San Bernardino.