Two heavily armed suspects - one male and one female - have been killed by police after a mass shooting in California left 14 people dead.
Police confirmed that the suspects were armed with assault rifles and handguns and wearing "assault-style clothing".
Hours earlier, the gunmen opened fire during a holiday party at a San Bernardino community centre.
Up to 17 people were wounded and the city virtually shut down as hundreds of officers searched for the gunmen.
The FBI is not ruling out the possibility of terrorism but the situation is still being investigated.
"They came prepared to do what they did, as if they were on a mission," San Bernardino Police Chief Jarrod Burguan said.
A third person who was running near the gun battle was detained, but he said it was unclear if that person had anything to do with the shooting.
Authorities are also evaluating a possible explosive device at the Inland Regional Center, where the shooting took place.
Hundreds of people were evacuated from the health care centre as police officers swept through the massive complex.
Others locked themselves in rooms waiting for police to arrive.
"People shot. In the office waiting for cops. Pray for us. I am locked in an office," Terry Petit's daughter texted him from inside the centre.
The Inland Regional Center specialises in helping adults with disabilities like autism and mental health problems, but the shooting appeared to be unrelated to the patients.
The attack took place in a conference area where the San Bernardino County Department of Public Health was holding a social event, said Maybeth Field, the centre's president.
The incident marks the deadliest mass shooting in the US since 26 people were killed at a Connecticut school in 2012. It comes just days after five people were killed at a Colorado Planned Parenthood clinic.
US President Barack Obama said in response 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.
"There are some steps that we could take, not to eliminate all incidents, but to make sure they happen less frequently."