Two shooters killed 14 people at a county holiday party yesterday in San Bernardino, California, in the deadliest mass shooting in the United States since Sandy Hook three years ago.�

The two suspects, Rizwan Farook and Tashfeen Malik, were killed in a shootout hours after the original attack. Officials believe that Malik was the girlfriend or wife of Farook, who had attended the holiday party.�

He left "under circumstances described as angry or something of that nature," according to San Bernardino Police Chief Jarrod Burguan. Farook returned with Malik and opened fire on the party.�

However, officials said there was some degree of planning that went into the shooting�the guns, masks, and tactical gear used were not used "on a spur-of-the-moment thing," Burguan said.�

"They came prepared for what they did and they were on a mission," Burguan explained in a press conference yesterday. "They came in with a purpose. They came in with the intent to do something."

After the couple opened fire, they fled in an SUV to the nearby city of Redlands, throwing pipe bombs out the windows as they drove away. A multi-hour standoff and shootout resulted in the deaths of the shooters.�

A third person was taken into custody in connection with the incident, but officers say they are confident there were only two shooters. Three explosives devices were also found at the scene of the shooting. Officials say they have not ruled out terrorism as a motive.?

The shooters targeted the offices of the Inland Regional Center,? a facility that serves people with developmental disabilities. Initial reports of gunfire came at around 11 a.m. local time after three suspects entered the center and opened fire. Law enforcement and emergency medical agencies immediately responded, and remain on the scene. The FBI and the Bureau of Alcohol, Tobacco, Firearms, and Explosives also dispatched agents to the center.

While authorities continued to search for Farook and Malik, all San Bernardino City Unified School District schools and offices were placed on full lockdown "for the safety of students and staff,"�The Los Angeles Times reports.�

President Barack Obama was conducting an interview with CBS News at the time of the shooting. He was briefed and told the interviewer that gun control legislation could reduce the chances of similar shootings recurring.

"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, and there's 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," Obama explained.�?

Inland opened in 1971 and is a nonprofit agency that serves individuals from San Bernardino and Riverside Counties. It has 670 staff members that serve more than 30,200 people, according to itsFacebook page.�?