The Big Read: California shootings - the world watches in horror at San Bernadino

San Bernardino Police Chief Jarrod Burguan speaks with the media regarding the mass shooting that occurred at the Inland Regional Center. Photo / Getty Images

They came prepared, assault rifles at the ready and their faces hidden by ski masks. Their victims were anything but prepared as they opened fire.

Just a few minutes later, they were gone, leaving 14 innocent people dead and another 17 wounded.

All hell broke loose in San Bernadino.

The world watched on in horror as the tragic drama unfolded and the hunt for the shooters began.

At 11am, a group of county employees were gathered for a Christmas function in a conference room at the Inland Regional Centre in San Bernadino, California.

The centre offers social services for people with developmental disabilities. However, the conference room had been hired by the outside group. Gunfire erupted in the room just after 11.

What exactly happened inside the room is still being pieced together by police and the FBI. But survivor stories paint a terrifying picture.

Denise Peraza, 27, was shot once. She called her sister from her hospital bed and her account was relayed to the Los Angeles Times.

Ms Peraza said all of a sudden the doors of the conference room opened and two men dressed in black and wearing face masks entered with "big ol' guns" and started shooting.

"Everyone dropped to the floor," Ms Peraza told her sister.

"The guys opened fired for 30 seconds, randomly, then paused to reload and began firing again."

As Ms Peraza cowered under a desk, she was shot in the lower back.

FBI agents huddle together after a mass shooting at the Inland Regional Center. Photo / Getty Images

Nearby, Kevin Ortiz was shot twice in the leg and once in the shoulder. Despite being badly injured, he managed to call his wife of two weeks, 23-year-old Dyana, and his father to tell them he was alive.

"Kevin said he had been shot three times and that he was in pain but he was all right," Mrs Ortiz told the LA Times." Then he said, 'I love you', and I said, 'I love you'."

Mr Ortiz, a county environmental inspector, made the call at 11.25am. He then called his father, Carlos Ortiz.

"Kevin called me immediately after he got shot and said: 'I've been shot three times, Dad. I'm in pain. Don't worry. There's a policeman with me'."

By then there were police on the scene, armed and hunting for the killers. They cleared buildings and through speaking to witnesses, built up a picture of the deadly trio, who had fled in a black SUV after the rampage.

News of the shooting began to spread and made headlines across the world. As the media swarmed, paramedics set up a triage facility and started to assess the injured. Survivors were bussed out of the area in school buses.

Reporters who got to the scene first described the horror. NBC Los Angeles reporter Tony Shin was near the triage area.

"They were being carried on trucks. They were shot, they were injured. Some of them did not survive," she said.

NBC cameraman Alex Vasquez could still hear gunfire when he arrived to start filming.

"I saw a woman take her last breath," he told his network.

An explosive device was found in the centre and as the bomb squad arranged for robots to help ascertain exactly what they were dealing with, Swat teams assembled and FBI agents joined the hunt for the shooters.

Police were getting calls by the minute from residents who thought they had spotted them. Officers searched cars, evacuated a shopping mall and shut down public transport and buildings.

San Bernardino police offices in SWAT gear secure the scene where a mass shooting occurred at the Inland Regional Center. Photo / Getty Images

They also stopped numerous "suspicious looking" people but it wasn't until a black SUV was seen driving quickly down one of the city's main streets that things began to heat up.

As patrol cars followed the vehicle, it sped up.

The driver refused to stop and then items thought to be pipe bombs, but later found to be non-explosive, were thrown from the back windows and shots were fired at the police.One officer was injured and when the SUV finally stopped, his colleagues returned fire.

Over the police radio, the sound of gunfire rang out."Multiple shots fired," an officer shouted at the dispatcher.

"We need medical aid."

Shortly after, he added: "Right now we have one down outside the [suspects'] car, one down inside the car and from what we understand one's on the run."

When officers were able to get to the vehicle, they found a man dead and a woman in the back seat. She had a gunshot wound but was breathing. She had a high-powered assault rifle strapped to her chest.

Bureau of Alcohol, Tobacco and Firearms spokeswoman Meredith Davis said the thick-gauge copper pipe was equipped with a piece of material made to look like a wick but was not a bomb.She said the pair found first were each armed with a long gun and a handgun, and wearing clothing "loaded with magazines for a gunfight".

Authorities traced the serial numbers on the guns and Swat teams were dispatched to related addresses. A third person was taken into police custody but it later emerged they were not linked to the shooting. The third suspect, also a woman, remains on the run.

Police chief Jarrod Burguan said authorities were looking into the motive for the attack. It is understood the male gunman worked for the county and recently had a dispute with fellow employees.

"A witness told police that although the gunmen had their faces covered, one of them sounded and appeared very similar to an employee who had left the facility earlier in the day," a law enforcement official told the LA Times.

Mr Burguan said: "I have heard that they were in a meeting or a holiday-type party event. A person did leave and there was some sort of dispute, but we have no idea if that was the people that came back."

US Security Forces secure the area following a shooting that killed multiple people at a social services center for the disabled in San Bernardino. Photo / Getty Images

US police tonight said they believed there were only two shooters involved - Syed Farook, 28, and his wife Tashfeen Malik, 27.

The pair have a child together, born this year.

A co-worker of Farook's, Patrick Baccari, confirmed Farook had been at the Christmas party earlier in the day and had been sitting at the same table as him.

Farook suddenly disappeared - leaving his coat on his chair.

Mr Baccari said the reserved Farook showed no signs of unusual behaviour, although he grew out his beard several months ago.

Mr Baccari had stepped into the bathroom when the shooting started and suffered minor wounds from shrapnel slicing through the wall.

US President Barack Obama sent his sympathies to the families of those who killed, adding that there was a "pattern of mass shootings" in the US that had "no parallel anywhere else in the world".