Up to three gunmen opened fire inside a centre for the disabled in San Bernardino, California on Wednesday (Dec 2), killing at least 14 people and and triggering a dramatic street shootout as police hunted down the suspects.
The deadly incident was the latest in a series of mass shootings in the United States, a spiral of violence that has exasperated President Barack Obama, who once again urged Congress to pass tougher gun control measures.
Hours after the attack at the Inland Regional Center in San Bernardino, local police engaged in a shootout with what they believed to be the attackers' vehicle, a black SUV.
Two suspects, one male and one female, were dead at the scene, San Bernardino police chief Jarrod Burguan announced in a news conference.
"They are both armed with assault rifles and handguns," he told reporters, adding that investigators were looking at the possibility that the suspects had left an explosive device at the scene of the shooting.
One person was detained. However, police "do not know the extent of his involvement if any".
According to the authorities, someone had been seen leaving a holiday party at the Inland Regional Center after "some sort of dispute".
Earlier on Wednesday, police were hunting for up to three gunmen following the attack, which also left 17 people injured.
One police officer suffered a non life-threatening injury during a shootout, Sergeant Vicki Cervantes said.
A body and what appeared to be a pool of blood could be seen near a bullet-riddled SUV that was surrounded by dozens of police vehicles.
Police swarmed the residential neighborhood with officers, guns drawn, as residents were told to stay in their homes with the doors locked.
DEADLIEST SINCE SANDY HOOK
A massive manhunt was launched for the suspects after the late morning shooting at the Inland Regional Center, which is about an hour's drive east of Los Angeles.
It was the country's deadliest shooting since December 14, 2012, when a young man killed 26 people, including 20 children at Sandy Hook elementary school in Newtown, Connecticut.
San Bernardino police chief Jarrod Burguan told reporters the shooters were armed with long guns and "came prepared to do what they did, as if they were on a mission."
He said that while the motive and identities of the attackers were not yet known, "at a minimum, we have a domestic terrorist type situation that occurred here."
"The preliminary number we have right now is that there are 14 people that are deceased. And our count is another 14 people that have been taken to various hospitals for significant injuries," Burguan said.
San Bernardino County Sheriff John McMahon said courts and local city and county buildings in the region had been placed on lockdown, and police presence had been boosted at area schools as the manhunt for the suspects continued.
Heavily armed SWAT teams, firefighters and ambulances swarmed the scene, as police warned residents away.
The attack took place inside a packed auditorium at the Inland Regional Center, a huge facility that employs several hundred people and assists people with developmental disabilities.
Brandon Hunt, who works at the center, said a banquet for county personnel was being held at the auditorium.
Lavinia Johnson, the center's executive director, said her staff waited inside the building after the shooting to be evacuated by police. "It was a very traumatic event for us," she told CNN.
Officials earlier said police went through the building room by room to check reports of a suspicious package that may have been left by the gunmen.
Family members of employees at the site rushed to the area on hearing of the shooting and were seen frantically trying to get information about their loves ones. "It was an hour until I learned my daughter was OK," said Olivia Navarro, 63. "She was frightened when I spoke to her but she seemed calm."
'STOP GUN VIOLENCE'
Obama, who just last week made a plea for action on gun control after three people were killed at a family planning center in Colorado, again voiced anger.
"The one thing we do know is that we have a pattern now of mass shootings in this country that has no parallel anywhere else in the world," Obama told CBS News.
"There are some steps we could take, not to eliminate every one of these mass shootings, but to improve the odds that they don't happen as frequently."
The Democratic presidential hopeful Hillary Clinton tweeted: "I refuse to accept this as normal. We must take action to stop gun violence now."
The city fire department said on Twitter it responded to initial reports of a "20 victim shooting incident."
Television footage showed dozens of people coming out of the building with their hands raised and walking to a parking lot, ringed by heavily armed police.
A spokeswoman for Loma Linda University Medical Center said it was expecting an unknown number of patients from the shooting, according to CNN.
Inland Regional Center serves thousands of people with developmental disabilities in San Bernardino and Riverside counties, according to its Facebook page.
The center provides services to more than 30,200 people.
Wednesday's shooting was certain to further stoke the bitter debate about gun control in the United States.
In Oregon in October, a gunman killed nine people at a community college before turning the gun on himself.
According to the site Mass Shooting Tracker, there have been 351 mass shootings in the United States so far this year. A mass shooting is defined as four or more people shot in one incident.