By Arun Kumar

Washington, Dec 5 (IANS): The FBI is investigating the California massacre as "an act of terrorism," after a revelation that the Pakistani-American female shooter posted a pledge of allegiance to ISIS leader Abu Bakr al-Baghdadi on Facebook during the shooting.

Tashfeen Malik, who with her US born Pakistani origin husband Syed Rizwan Farook, shot dead 14 people and wounded 21 others during a holiday party in San Bernardino, California, Wednesday made the post on an account with a
different name,

Officials did not explain how they knew Malik made the post, CNN said. But hours later FBI official David Bowdich announced Friday that Wednesday's mass shooting is now being investigated as "an act of terrorism."

FBI had "uncovered evidence ... of extreme planning," said Bowdich, assistant director of the FBI office in Los Angeles, and some phone conversations between at least one of the shooters and other people are being investigated.

A Facebook official told CNN that a post that went up about 11 a.m. Wednesday that violated the company's community standards that prohibit the promotion of terrorism or the glorification of violence. It was taken down Thursday.

The mass shooting may have been inspired by ISIS, a law enforcement official cited by CNN said, but none of the officials said ISIS directed or ordered the attack.

"This is looking more and more like self-radicalization," a law enforcement official said.

Neither Farook nor his wife was on any list of potentially radicalized people, according to police. But it's not known what connections Malik, who was born and raised in Pakistan and moved to Saudi Arabia about the age of 19, had with any terrorists or groups.

Malik, 27, arrived in the US on a K-1, or fiancée, visa and attained permanent resident status by virtue of their marriage two years ago.

Farook, 28, who was born in Chicago, and Malik, 27, were killed in a shootout with police a few miles away more than four hours after the rampage.

Authorities said they are still trying to determine why Farook and his wife attacked the Inland Regional Centre.

"There was obviously a mission here," Bowdich said. "We do not know why. We do not know if this was the intended target or something triggered him."

NBC News cited unnamed officials as saying that Farook appeared to have been radicalized. They said he had been in touch with people in the Los Angeles area who have expressed jihadi-oriented views.

Intelligence sources told NBC News that Farook appeared to have been in some form of communication with people overseas who are persons of interest to US authorities.

In May, Farook and Malik had a baby, whom they left with Farook's mother, claiming they they had a doctor's appointment, said Farhan Khan, Farook's brother-in-law.

The grandparents first became worried when they got a call from the media about 2 p.m. asking whether they knew that Farook was a suspect, Khan, who is married to Farook's sister, told NBC News.

A profile under the user name "farooksyed49" on the dating website iMilap.com, which describes itself as a "Site for People with Disabilities and Second Marriage," featured a picture of Farook, which Khan confirmed was his brother-in-law.

The user said he was from a "religious but modern family" and listed "Eastern and Western Mix" under family values.

"Enjoy working on vintage and modern cars, read religious books, enjoy eating out sometimes travel and just hang out in back yard doing target practice with younger sister and friends," according to the profile.