SAN BERNARDINO, United States (AFP) – America’s epidemic of gun violence has struck again and claimed 14 lives, this time at the hands of a heavily armed man and woman who shot up a Christmas party in California and were later gunned down by police.

It was the worst mass shooting in three years. Police said they did not yet know the motive but did not rule out terrorism in Wednesday’s slaughter.

Police identified the pair as Syed Farook, a 28-year-old US citizen who worked for the local county as an environmental inspector, and Tashfeen Malik, 27, whose nationality was unknown. They said the suspects were either married or engaged.

Jarrod Burguan, San Bernardino’s police chief, confirmed that both were killed in a shootout in which police chased and then surrounded a black SUV.

The role of a third detainee caught fleeing from the scene is not clear but he is not believed to have been a shooter, Burguan added.

The shooters targeted a year-end party taking place at a social services center in San Bernardino, about an hour’s drive east of Los Angeles. Besides the fatalities, 17 other people were wounded.

“We don’t have the motive at this point,” the police chief said. “We have not ruled out terrorism.”

According to the site Mass Shooting Tracker, the latest attack brings to 352 the number of mass shootings in the United States so far this year. A mass shooting is defined as four or more people shot in one incident.

The massacre drew an angry response from President Barack Obama, who once again urged Congress to pass tougher gun control measures to stem America’s epidemic of gun violence.

Farook had worked for the county health department for five years, Burguan said.

He and Malik were dressed in military-style gear and carried assault weapons as they burst into an auditorium let out for the holiday party by the Inland Regional Center for the disabled.

Burguan said Farook had attended the Christmas party organized by the health department and left after an apparent dispute, only to return a short time later with Malik, armed with assault rifles and semiautomatic handguns.

“Based upon how they were equipped, there had to be some degree of planning that went into this,” he said. “I don’t think they just ran home and put on these tactical clothes, grabbed guns and came back on a spur of the moment thing.”

– ‘In shock’ –

There was no immediate information on the identity of the victims.

The California chapter of the Council on American-Islamic Relations (CAIR) denounced the killings.

Farook’s brother-in-law, Farhan Khan, said he had no clue what prompted the carnage.

“I am in shock that something like this could happen,” a visibly shaken Khan told a press conference organized by CAIR.

Khan said Malik was Farook’s wife and they left their six-month-old daughter with Farook’s mother earlier in the day on the pretext that they had a doctor’s appointment, Khan told NBC News separately.  

The Los Angeles Times quoted some of Farook’s co-workers as saying he had previously traveled to Saudi Arabia and returned with a new wife. The couple appeared to be “living the American dream,” Patrick Baccari, a fellow inspector who shared a cubicle with Farook, told the paper.

Baccari and other co-workers told the Times Farook was a devout Muslim who kept to himself and rarely discussed religion at work.

“He never struck me as a fanatic, he never struck me as suspicious,” Griselda Reisinger, who worked with Farook until changing jobs in May, told the paper.

– Deadliest since Sandy Hook –

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.

Witnesses at the California scene recounted barricading themselves in offices and hiding as the sound of gunfire erupted.

Mark Stutte said his daughter was attending the party organized by the county’s public health department and called him terrified while hiding in a restroom as gunshots rang out in the background.

“It was really, really super scary,” he told local TV, as he wept. “I’m far away. I couldn’t do anything for her.”

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, voiced his anger once more. 

“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,” he 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.”

Wednesday’s shooting was certain to further stoke the bitter debate about gun control in the United States.