Two shooters have been identified as Fyed Farook, 28, and Tashfee Malik, 27. No motive has been identified and the pair were married.
Colleagues have said that Farook, 28, was a environmental health specialist for five years, part of San Bernardino County’s public health department which was holding the party he attacked.
Farhan Khan, the brother-in-law of Farook, told a news conference that he last spoke to Farook a week ago.
“I have no idea why he’d do it,” he said. “Why would he do it? Why would he do something like this?
“I’m in shock myself. I am a normal person.”
SB police : Syed Farook was at work and attended holiday party & left early. He was employee of SB county pic.twitter.com/NtqE2WuY3w
— Tara Wallis (@tarawallis) December 3, 2015
The Times said Farook had recently traveled to Saudi Arabia and came back to the U.S. with a wife that he had met online.
There is little detail at the moment about the second shooter, Tashfeen Malik.
San Bernardino police chief Jarrod Burguan said she was 27 years old.
Mr Burguan said: “We’re pretty comfortable that the two shooters that went into the building are the two shooters deceased on San Bernardino Avenue.”
“The first one is Syed, Rizwan, last name Farook. He is 28 years old. I am told that he is US-born. The person that was with him is a female. Her name is Tashfeen, last name Malik. She is 27 years old.”
The couple leave behind a baby who is six months old.