Obama briefed on radicalization of California shooters

US President Barack Obama on Saturday was briefed on information which points to radicalisation of the two shooters who gunned down 14 people and injured 21 others on Wednesday in San Bernardino, Southern California, the White House said here on Saturday.

"The President's team highlighted several pieces of information that point to the perpetrators being radicalised to violence to commit these heinous attacks," said the White House in a statement after Obama's meeting with leaders of US law enforcement and intelligence community.

"The President's team also affirmed that they had as of yet uncovered no indication the killers were part of an organised group or formed part of a broader terrorist cell."

The two shooting suspects, 28-year-old US citizen Syed Rizwan Farook and his 27-year-old wife Tashfeen Malik, had 1,600 rifle and 9-millimeter rounds of ammunition when they were killed, and 2,000 9-millimeter rounds and 2,500 0.223 rifle rounds at their rental home, as well as 12 pipe bombs and tools to make bombs.

Those did not include the hundreds of rounds the two killers fired in the shootout with police, according to police sources.

Local police sources said "some degree of planning" was involved in the shooting spree.

The US Federal Bureau of Investigation on Friday announced it was investigating the case as an act of terrorism.

It was also revealed on Friday that Malik, the woman shooter in the carnage, pledged allegiance to the Islamic State the terrorist group on social media.