One US official familiar with the investigation said Malik had posted on Facebook under an account with a different name. The officials did not explain how they knew Malik was responsible for the post, CNN reported.
Malik and her American husband, Syed Farook, burst into a year-end party in San Bernardino, California Wednesday and opened fire on a roomful of Farook's co-workers, killing 14 and wounding 21.
Pakistani-origin couple kept tight lid on plans for San Bernardino shooting
"At this point we believe they were more self-radicalized and inspired by the group than actually told to do the shooting," an official told the New York Times, which also reported that Malik had pledged allegiance to IS in a Facebook posting but that there was no evidence the group directed the woman.
FBI agents have been combing through cellphones and a computer hard drive left behind by the couple to try to establish a motive for the killings.
CNN, quoting officials, earlier said Farook had been in contact with known terror suspects overseas and had become radicalized after marrying Malik in Saudi Arabia last year, although an imam at a local mosque he attended said Farook showed no signs of that.
The Times reported that the FBI had evidence Farook had communicated with extremists domestically and abroad a few years ago.
Tashfeen Malik studied at Bahauddin Zakariya University in Multan
Malik moved to Saudi Arabia from Pakistan about 25 years ago but returned home to study to become a pharmacist, two Pakistani officials told Reuters. Malik, 27, was from the Layyah district in southern Punjab, the officials said.
She returned to Pakistan five or six years ago to complete a degree from Bahauddin Zakariya University in Multan, they said. A family member said he had been contacted by Pakistani intelligence as part of the investigation of Wednesday's deadly shooting in San Bernardino, California.
California shooting being investigated as an act of 'terrorism': FBI
The Federal Bureau of Investigation has said it is investigating the massacre as "act of terrorism."
"Based on the information and the facts as we know them, we are now investigating these horrific acts as an act of terrorism," David Bowdich, assistant director of the FBI's Los Angeles office, told reporters.
Investigators have determined that the Malik and Farook engaged in extensive planning before the attack, he said.
Bowdich added the FBI also was examining crushed cellphones found near the shooting scene and had established that there were "telephonic connections" between the couple and other people of interest in FBI probes.
COMMENTS (20)
Comments are moderated and generally will be posted if they are on-topic and not abusive.
For more information, please see our Comments FAQ