The female suspect in the California gun attack pledged allegiance to the leader of the Islamic State group on Facebook, US officials say.
Tashfeen Malik made the post under an account with a different name, the officials told US media.
Fourteen people were killed and 21 wounded in Wednesday’s attack.
Malik and her husband Syed Rizwan Farook, age 28, died in a shootout with police after the killings at San Bernardino, west of Los Angeles.
The New York Times reported that there was no evidence that Islamic State had directed the couple in the attack.
“At this point we believe they were more self-radicalised and inspired by the group than actually told to do the shooting,” the newspaper quoted an official as saying.