At least 14 people have been killed in a mass shooting in California involving up to three gunmen, the BBC reported.

Officers said 18 people were also wounded in the attack at a social service centrer in San Bernardino.

The gunmen, wearing military-style clothing and armed with long guns, opened fire at the Inland Regional Center, which helps adults with disabilities.

Witnesses said people locked themselves in offices as the gunfire rang out.

Hours after the attack, police hunting for the attackers riddled a black SUV with gunfire in a residential area several miles away.

The attack took place in a conference area where the San Bernardino County Department of Public Health was holding a social event.

President Barack Obama has responded to the shooting.

"One thing we do know is that we have a pattern of mass shootings in this country that has no parallel anywhere in the world," he said.

"There are some steps that we could take, not to eliminate all incidents, but to make sure they happen less frequently."

Sources: MENA