Police have identified two people suspected of opening fire at a California social services center Wednesday, killing 14 people, before being later shot dead by police.

Syed Farook, 28, and Tashfeen Malik, 27, were killed in a shootout with police more than four hours after the shootings at the Inland Regional Center in San Bernardino, police said.

"It really looks like we have two shooters, and we’re pretty comfortable that the two shooters that we believe went into the building are the two shooters that are deceased," San Bernardino Police Chief Jarrod Burguan told reporters Wednesday night.

A motive in the shooting has not been determined, Burguan said.

"I just cannot express how sad I am for what happened today," Farook's brother-in-law, Farhan Khan, said at a press conference held by the Muslim civil liberties and advocacy group the Council on American-Islamic Relations Wednesday night.

"My condolences to the people who lost their life ... I am in shock that something like this could happen," Khan said. Khan is married to Farook's sister

The shooting at the Inland Regional Center occurred at around 11 a.m. Police said two shooters barged into a conference room during a Christmas party for San Bernardino County employees and opened fire before fleeing in a black sport-utility vehicle.

Farook, an employee of the county health department for five years, where he was an environmental specialist, was at that party, Burguan said.

"He was at the party, he did leave the party under some circumstances that were described as angry," Burguan said.

Between 10 and 30 minutes passed from when Farook left the party and the shooting, Burguan said.

Explosive devices were found in the center after the shooting, and Farook and Malik were wearing "assault-style clothing" and armed with assault-style rifles when they were killed, Burguan said.

Farook and Malik were either married or engaged to be married, Burguan said. Farook was born in the U.S., Burguan said. He couldn't provide more details about Malik.

Khan said he spoke with Farook about a week ago. "I have no idea why he would do that, why he would do something like this,” Khan said. "I am in shock myself."

Farook and Malik lived with Farook's mother in Redlands, Khan said, and they have a 6-month-old daughter.

Prior to the shooting Wednesday, they left the child with Farook's mother and said one of them had a doctor's appointment, Khan said. It wasn't clear exactly when the child was left.

The information about Farook leaving the party early led investigators to a home in Redlands where he is listed as a resident, Burguan said. It was there that the suspect vehicle was spotted and the police pursuit that ended in gunfire began, he said.

That home was surrounded by law enforcement officers Wednesday night. An ATF official said a robot was sent inside to sweep the home for explosives.

The FBI and the federal Bureau of Alcohol, Tobacco, Firearms and Explosives are also investigating the shooting. The ATF said two rifles and two handguns were recovered.

Two of those weapons were bought legally by someone involved in the investigation, sources familiar with the police investigation told NBC News.

Both suspects were armed with "what was essentially a .223-caliber assault rifle,” Burguan said. One was a DPMS A-15 and one was a Smith & Wesson M&P15, he said. They also had semi-automatic handguns, he said.

"I think that based upon what we have seen and based upon how they were equipped, there had to be some degree of planning that went into this,” Burguan said. "So I don’t think they just ran home, put on these types of tactical clothes, grabbed guns and came back on a spur of the moment.”