Two people opened fire at a party at a social services agency in San Bernardino, California, killing 14 people and wounding 17 others before fleeing, authorities said.
An intense manhunt got under way for a number of suspects who carried out the attack at Loma Linda University Medical Centre.
Just got to Loma Linda Univ. Medical Center. Here is what the emergency center looks like from above. #SanBernadino pic.twitter.com/daLkADHI3G
— Erika Aguilar (@erikaaaguilar) December 2, 2015
San Bernardino police reported one "suspect down" in an exchange of gunfire with officers and police said one suspect was still at large.
Olivia Navarro spoke w her daughter when she was still inside. She said she turned all the lights off, stayed quiet pic.twitter.com/aBSeulgEfP
— Sarah Parvini (@sarahparvini) December 2, 2015
San Bernardino Police Chief Jarrod Burguan said in a televised news briefing three hours after the shooting that the suspects were believed to have made their getaway in a dark-coloured sport utility vehicle.
A vehicle matching that description turned up at the shootout with police several hours later, city police spokeswoman Sergeant Vicki Cervantes.
She said the number of wounded rose to 17.
With suspects at large, authorities ordered a security "lockdown" of all local schools, as well as city and county buildings, and area hospitals were placed on alert, Mr Burguan said.
Mr Burguan said he knew of no possible motive behind the attack, which unfolded at about 11am local time.
"We have no information at this point that this is terrorist-related, in the traditional sense that people may be thinking," he added.
"Obviously, at minimum, we have a domestic-type terrorist-type situation that occurred here."
He said the suspects were armed with rifles.
#SanBernadinoShooting evacuated workers pray together on golf course across street from mass #shooting pic.twitter.com/QyB6UYwocl
— Gina Ferazzi (@GinaFerazzi) December 2, 2015
One man whose son works in the building where the shooting took place said he received text messages from his son who told him he saw three shooters enter the building.
"He said there were multiple wounded and fatalities," the man told the local television station KABC.
The White House said President Barack Obama had been "briefed by his Homeland Security Advisor Lisa Monaco about the shooting and had asked to be updated on the situation as it develops."
I refuse to accept this as normal. We must take action to stop gun violence now. -H https://t.co/SkKglwQycb
— Hillary Clinton (@HillaryClinton) December 2, 2015
The Democratic presidential hopeful Hillary Clinton tweeted: "I refuse to accept this as normal. We must take action to stop gun violence now."
The shooting took place near a golf course where an employee told AFP that staff had been told to stop all activities.
The man, who did not want his name used, said the area houses office and industrial buildings.
He said there were also government offices in the area.
Inland Regional Centre, the reported site of the shooting, serves thousands of people with developmental disabilities in San Bernardino and Riverside counties, according to its Facebook page.
The centre has nearly 670 staff at its locations in the two counties providing services to more than 30,200 people.
The shooting comes just days after a lone gunman killed three people during a standoff at a Planned Parenthood clinic in Colorado.
It was certain to further stoke the controversy about gun control in the United States, where shootings are a part of daily life.
