San Bernardino shooting: Family of Syed Rizwan Farook and Tashfeen Malik 'in complete shock'

Farook's sister said she could not understand why the couple would commit such an atrocity

The family of the husband and wife who massacred 14 people at a work party in California have expressed their shock and said they wished they could have stopped the atrocity.

Saira Khan, the sister of suspected gunman Syed Rizwan Farook told CBS News she never could have imagined her “happily married” brother and sister-in-law leaving their six-month-old daughter to commit such a horrific crime.

“We're also mourning the loss of someone we knew, or we thought we knew,” she added. "So many things I asked myself.

“I ask myself if I had called him that morning or the night before, asked him how he was doing, what he was up to. If I had any inclination, maybe I could have stopped it.”

Lawyers representing the family said relatives were “in complete shock” and had no idea Farook and his wife, Tashfeen Malik, were capable of such an attack.

Warning against jumping to conclusions after the FBI said earlier the attack was being investigated as an “act of terrorism”, attorneys David Chesley and Mohamed Abuershaid said there was no evidence that the couple were members of a militant group.

An anonymous US official said Malik used a Facebook alias to pledge her allegiance to Isis and its leader, Abu Bakr al-Baghdadi just before the shootings.

Malik, 27, and her 28-year-old husband died in a shootout with police after killing 14 people and injuring 21 more in San Bernardino, east of Los Angeles.

Tashfeen Malik, left, and Syed Farook died in a shoot-out with police (AP)

FBI officers searching their suburban home afterwards found more than 4,500 bullets, 12 pipe bombs and enough equipment to build several more

Farook, who was known to own two handguns by friends, has been described by colleagues as an isolated man who “changed” after returning from Saudi Arabia, where he met his wife on the Hajj pilgrimage.

His brother, Syed Raheel Farook , is a decorated serviceman from the US Navy.

He was awarded the Global War on Terrorism Expeditionary Medal and the Global War on Terrorism Service Medal, among other awards for his service aboard the USS Enterprise as an information system technician from 2003 to 2007.

Malik was described by family as a “caring, soft-spoken” housewife who was very conservative, wearing a burka and refusing to drive or interact with male family members.

The FBI announced yesterday that it is investigating the mass shooting as an act of terror.

Director James Comey said there was no indication yet that the plot was directed by any other foreign terror group but that the couple may have been “inspired”.

“The investigation so far has developed indications of radicalisation by the killers and of potential inspiration by foreign terrorist organisations,” he said, saying there was no evidence the shooters were part of a wider group.

If proven to be terrorism, it would be the deadliest attack by Islamic extremists on American soil since 9/11.

Additional reporting by AP