Authorities are working to determine why a man and a woman opened fire at a holiday party of his co-workers in Southern California yesterday, killing 14 people and wounding 21 in what appeared to be a planned attack.
Syed Rizwan Farook, 28, and Tashfeen Malik, 27, who had a six-month-old daughter together, were killed in a shootout with police after the mass shooting at the Inland Regional Centre in the city of San Bernardino, a social services agency where Farook worked as an inspector.
Officials from San Bernardino Police Chief Jarrod Burguan to President Barack Obama said the attack may have been an act of terrorism but that a motive had not yet been determined.
"It is possible that this was terrorist-related. But we don't know," Obama told reporters at the White House. "It is also possible that this was workplace-related."
"Rest assured that we will get to the bottom of this," said Obama, who said the FBI was taking over the investigation of the attack.
Farook, a US citizen, was born in Illinois, the son of Pakistani immigrants, according to Hussam Ayloush, who heads the Los Angeles area chapter of the Muslim advocacy group Council on American-Islamic Relations (CAIR).
Malik, his wife, was born in Pakistan and had been living in Saudi Arabia before marrying Syed, Ayloush said. Both were Muslims, Ayloush said.
Officials in Washington familiar with the investigation said so far there was no hard evidence of a direct connection between the shooters and any foreign militant group. The sources said a raid on a townhouse believed used by the couple was searched for electronic devices that could show if they had shown interest in Jihadist websites or social media.
The two assault rifles and two handguns recovered from the shootout were legally purchased in the United States, said a spokeswoman for the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF). Two of them were purchased by someone "associated with this investigation," while the buyer of the other two was not linked to the investigation, she said.
The long guns were .223-caliber and their ammunition can go through protective vests and walls, Davis said.
In addition to further debate on gun control laws, the latest mass slaying in the United States comes with much of the world on edge following attacks in Paris by Islamic State militants that killed 130 people last month.
The Los Angeles Times reported that co-workers described Syed Farook as quiet and polite.
Hussam Ayloush appealed to the public not to jump to conclusions about the suspects' motives. He said he was concerned about a backlash against the broader Muslim community in view of the rise of Islamic State and some opposition among politicians and the public in the United States over US plans to accept Syrian war refugees.
Last night the brother in law of Syed Farook expressed his sadness and shock at the events.
"I have no idea why would he do that. Why would he do something like this? I have absolutely no idea. I am in shock myself," said an emotional Farhan Khan.
Police Chief Jarrod Burguan said the shootings broke out after Syed Farook, a county public health employee, attended the party at the Inland Regional Centre and, at some point, stormed out. He and Tashfeen Malik later returned, both dressed in assault-style clothing, and opened fire, Burguan said. They also placed several bombs at the scene, which police detonated, authorities said.
Jarrod Burguan said the manner in which the couple was equipped indicated there was "some degree of planning" behind the attack.
About five hours after the assault, police spotted Syed and Tashfeen in a vehicle about 3.2km away. The couple died in a shootout with police.
The San Bernardino rampage was the deadliest US shooting incident since the December 2012 massacre at Sandy Hook Elementary School in Newtown, Connecticut in which 27 people, including the gunman, were killed.
There have been more than 350 shootings this year in which four or more people were wounded or killed in the United States, according to the crowd-sourced website shootingtracker.com, which keeps a running tally of US gun violence.
"I don't think any community is immune," San Bernardino Mayor Carey Davis told CBS. "Certainly, we don't anticipate that kind of thing happening here. It was a shock."
Carey Davis said on Twitter he had a "heartfelt conversation" about the killings with Obama, who used the incident to make another call for gun law reform to reduce the likelihood of mass shootings.
"We have a no-fly list where people can't get on planes but those same people who we don't allow to fly could go into a store right now in the United States and buy a firearm and there's nothing that we can do to stop them," Obama said in an interview with CBS News on Thursday.