San Bernardino, California: Gunmen opened fire on a holiday party on Wednesday at a social services agency in San Bernardino, California, killing 14 people and wounding 17 others, then fled the scene, triggering an intense manhunt and a shootout with police, authorities said.

One suspect was struck by gunfire and one officer was injured in a confrontation hours after the mass shooting, San Bernardino police spokeswoman Sergeant Vicki Cervantes told reporters, adding that a second suspect might still be ‘outstanding.’

She did not know the condition of the struck suspect but said the officer’s injuries were not considered to be life-threatening.

San Bernardino Police Chief Jarrod Burguan said in a televised news briefing earlier that as many as three suspects were believed to have made their getaway in a dark-colored sport utility vehicle. A vehicle matching that description turned up at the shootout with police several hours later, Cervantes.

The police chief said 14 people were killed and 14 others wounded in the initial shooting spree, which unfolded at 11 a.m. on the campus of the Inland Regional Centre, an agency that serves the developmentally disabled.

Cervantes later revised the toll of wounded to 17, not including the suspect and police officer who were shot later.

The shooting rampage in San Bernardino, about 60 miles (100 km) east of Los Angeles, marked the deadliest US gun violence since the massacre at Sandy Hook Elementary School in Newtown, Connecticut, in December 2012, in which 27 people, including the gunman, were killed.

As the suspects fled, authorities ordered a security ‘lockdown’ of all local schools, as well as city and county buildings, and area hospitals were placed on alert, Burguan said. Police searched door to door in the Redlands neighbourhood a few miles from the site of the attack.

Burguan said he knew of no possible motive behind the attack.

‘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.

The Los Angeles Times, citing information from a senior federal official who was monitoring the case, reported that investigators believe one of the shooters left the party after getting into an argument and returned with one or two armed companions.

The Inland Regional Centre is one of 21 facilities set up by the state and run under contract by non-profit organizations to serve people with developmental disabilities, said Nancy Lungren, spokeswoman for the California Department of Developmental Services.

Lavinia Johnson, executive director of the facility, told CNN the suspects opened fire inside a conference building in the complex where a holiday party was being held for county health department personnel.

The conference building sits adjacent to the two larger three-story buildings that house most of the agency’s offices at the complex, Johnson said. Asked whether that meant that the Inland Regional Center staff and clients were safe, she said she understood they were being evacuated.

String of shootings

So far in 2015, there have been more than 350 shootings in which four or more people were wounded, according to the crowd-sourced website shootingtracker.com, which keeps a running tally of US gun violence.

The shooting in California comes less than a week after a gunman killed three people and wounded nine in a shooting rampage at a Planned Parenthood clinic in Colorado Springs, Colorado. In October, a gunman killed nine people at a college in Oregon, and in June, a white gunman killed nine black churchgoers in South Carolina.

Gun control advocates, including Democratic President Barack Obama, say easy access to firearms is a major factor in the shooting epidemic, while the National Rifle Association and other pro-gun advocates say the Second Amendment of the US Constitution guarantees Americans the right to bear arms.