Killer couple's cache of weapons photographed
Images have emerged of the guns and explosive devices used by the husband and wife who shot dead 14 people at a social services centre in California.
Syed Farook and Tashfeen Malik carried out the massacre while a party was being held in the building in San Bernardino on Wednesday.
A picture of the screen from the bomb squad robot shows three connected pipe bombs left behind, designed to be operated by a toy car remote control. They did not work.
Police said they found a dozen more pipe bombs in a bag and nearly 5,000 rounds of ammunition at the killers’ home.
Images of the assault rifles and guns they used have also been released, as well as a new photo of their truck peppered with bullet holes.
The pair had more than 1,600 bullets with them when they were shot dead in their rented black Ford Expedition - which was being pursued by 23 police officers.
Farook, a US-born restaurant inspector, had been in touch with Islamic extremists on social media, a US intelligence agency official said on Thursday.
However, the FBI has cautioned that it is still trying to confirm the motive for the shooting, which also injured 21 people.
"We don't know if this was workplace rage or something larger or a combination of both," Attorney General Loretta Lynch said in Washington.
Farook began the attack after leaving his Christmas party following an apparent dispute, leaving his coat on his chair
He returned a short time later with Malik - both of them dressed in black tactical gear and wielding weapons.
Farook, 28, also reportedly had an argument over religion two weeks ago with a Jewish co-worker killed in the attack.
Nicholas Thalasinos’ friend, Kuuleme Stephens, told Associated Press she had overheard the argument during a phone call.
Mr Thalasinos’s wife has admitted to KPCC radio that her husband "did have a lot of anti-Muslim sentiment".
It is not clear though if the alleged incident has any connection to the attack.
The first police officer to arrive at the scene of the shootings has also been speaking about the horror he faced.
"It was unspeakable," Lieutenant Mike Madden said.
"The carnage that we were seeing, the number of people who were injured and unfortunately already dead and the pure panic on the face of those individuals (still alive)."
Lieutenant Madden said he was forced to pass by injured people who needed help in order to stop the attackers.
A candlelight prayer vigil for the victims, who ranged in age from 26 to 60, was held on Thursday night at San Bernardino’s minor-league baseball park.
President Barack Obama, turning on the White House Christmas tree lights in Washington, called for national mourning following America's worst mass shooting for several years.
"Their loss is our loss too - but we’re all one American family. We look out for each other - in good times and in bad."