Syed Rizwan Farook, 28, was at the celebration for local health officials but reportedly left angry before returning heavily armed with wife Tashfeen Malik, 27, and opening fire at the city's Inland Regional Center Wednesday morning.

The two escaped the scene before being tracked by police to a home one city over. They sped away from the house in a black SUV, shooting at police out the back window and reportedly throwing pipe bombs before the two were shot dead. They were armed with assault rifles and semi-automatic handguns, according to Daily Mail.

One of the dead attackers outside the shot-out SUV. The suspect was killed in a police chase while still inside the vehicle, then moved on the street.

In the hours after the shooting, more information emerged about Farook, who was born in the U.S., and Malik, whom is he thought to have met and married in Saudi Arabia before bringing him home to Redlands, California with him.

Farook and Malik are thought to have married earlier this year in Saudi Arabia.

The Los Angeles Times reported that Farook met Malik online then traveled to Saudai Arabia to marry her. Colleagues told the Times that Farook rarely discussed about religion at work.

Fragments of video from witnesses on the ground showed the killers and officers exchanging gunfire on the roads of San Bernardino . The chase ended sometime between 3pm and 4pm Wednesday - as long as five hours after the massacre began.

Police have yet to offer a clear motive for the attack, though federal agencies have yet to rule out terrorism, and are hunting for links to ISIS and other extremist groups. Farook, was an environmental specialist with the county health department.

San Bernardino Police Chief Jarrod Burguan said that Farook was 'angry' when he left the party, before returning with Malik and a stash of heavy weapons. Burguan said that there was obviously 'some degree of planning involved' in the attack.

Police said a third person was detained. It is not clear whether they are connected to the incident.

The FBI are considering domestic terrorism and workplace violence as potential motives in the killing, which is the worst since Sandy Hook elementary school was attacked in 2012.

After Farook and Malik were killed, police served a search warrant on a home in Redlands, believed to be the one where the chase began.