Here is how the story unfolded - the first hours after the shooting, the police chase of the suspects' vehicle, the chase ending in gunfire, the identification of the suspects and search of their home, and the early speculation on potential links to terrorism.
San Bernardino County Sheriff John McMahon confirmed that the number of victims who have died is still 14. The names of the deceased victims will be released later in the day.
Twenty-one injured victims are being treated at various hospitals. One officer who was shot in the leg is being treated as is another officer who was sustained minor injuries from shrapnel.
According to Jarrod Burguan, San Bernardino's chief of police, about 300 officers from local, county, state and federal agencies responded to the initial active shooter call.
David Bowdich, assistant director of the FBI's Los Angeles office, confirmed that the suspects were married. Farook, a U.S. citizen, brought Malik to the U.S. in July 2014 after a trip to Pakistan. Malik became a legal permanent resident, obtaining a K1 visa, and the couple had a child.
Four guns were found on the suspects, two of which were purchased by Farook and two of which were purchased by a third person. All four guns were purchased legally. Burguan said he believes a degree of planning went into the mass shooting.
The two suspects, who were both killed in a shootout, traveled to a home in Redlands, California, in a black Ford Expedition that they had rented days earlier. More than 1,400 .223-caliber rounds were found in the car.
Twelve pipe bomb devices and hundreds of tools that could be used to construct improvised explosive devices and bombs were found inside the house and garage. Two-thousand 9mm rounds and 2,500 .223-caliber rounds were also found in the house.
No motive for the massacre has been identified. It's unclear if the suspects were planning another attack.
The investigation is ongoing. Authorities have not ruled out terrorism, and local media outlets have suggested that the incident may have resulted from a workplace dispute.
3:00 a.m. Thursday
The Associated Press reports that the two assault rifles and two handguns used in the San Bernardino shooting were all purchased legally in the United States. Federal authorities indicate that a person is under investigation in relation to two of the weapons.
10:55 p.m. Wednesday
The Associated Press is reporting that Farook traveled to Saudi Arabia earlier this year and returned with a wife, who was reportedly a pharmacist. The pair had a child together.
Co-worker Patrick Baccari says the reserved Farook showed no signs of unusual behavior, although he grew out his beard several months ago.
Baccari said that Farook left the party suddenly Wednesday, leaving his coat behind on his chair.
10:15 p.m. Wednesday
Authorities have positively identified two suspects in the San Bernardino shootings: Syed Farook, 28, and Tashfeen Malik, 27. The two suspects are believed to have been romantically involved. The Associated Press cites family members, who claim the two suspects were married. Both suspects are deceased.
Farook was an environmental specialist with the county health department who sometimes worked at the Inland Regional Center in San Bernardino.
San Bernardino Police Chief Jarrod Burguan told reporters that Farook angrily left an office holiday party earlier Wednesday before returning with Malik.
The couple reportedly left their baby with family Wednesday morning and never returned, according to The Associated Press.
Police have not ruled out terrorism, stating that evidence collected so far indicates there was some planning involved in the attack, and that it likely was not a spur-of-the-moment crime.
8:55 p.m. Wednesday
The brother-in-law of one of the suspects says he was stunned to hear of his relative's involvement in Wednesday's shooting.
Farhan Khan, who is married to the sister of Syed Farook, spoke to reporters at the Anaheim office of the Council on American-Islamic Relations.
Khan says he last spoke to Farook about a week ago. He added that he had "absolutely no idea why he would do this. I am shocked myself."
8:40 p.m. Wednesday
A second suspect in the shooting was identified but then the reporter said later it was a hoax.
7:40 p.m. Wednesday
Various media sources, including the Los Angeles Times, reported the identify of one of the suspects as Syed Farook.
Meredith Davis, a spokeswoman with ATF, told KCAL9-TV the two suspects who died in a shootout with police after the mass killing in California were each armed with a long gun and a handgun.
They were wearing tactical-style clothing that was "loaded with magazines for a gunfight," she said Wednesday.
Davis said the suspects also threw a thick-gauge copper pipe out of the SUV, but no explosives were found inside.
The fake pipe bomb was equipped with a piece of material made to look like a wick.
Authorities are tracing the serial numbers on the guns and authorities will be dispatched to those addresses.
6:40 p.m. Wednesday
Law enforcement officers are calling for people to come to the front door of a home in Redlands, California, where tips led authorities investigating the deadly shooting at a social services center.
One of them called out: "This is the FBI." Officers in riot gear, a bomb squad unit and armored vehicles are outside Wednesday night. They appear to have brought in robot devices.
It's unclear if anyone is inside the home.
San Bernardino Police Chief Jarrod Burguan said an SUV was seen leaving the residence earlier, leading to a police pursuit and a gunbattle that killed two suspects in the shooting that left 14 people dead in neighboring San Bernardino.
5:35 p.m. Wednesday
At a formal news conference, San Bernardino Police Chief Jarrod Burguan said tips led investigators to a neighborhood in Redlands, where they spotted the SUV that led them on a chase.
An officer was wounded during an exchange of gunfire at the end of the chase. The officer was expected to recover fully. Two suspects, a male and female, were dead at the scene, Burguan said. He said those two were the only people in the SUV. He said a third person who was seen running from the scene of the shootout was detained and was being questioned.
Burguan said both suspects were armed with assault rifles and handguns and may have planted explosive devices in the building where the attack took place. The SUV was also being checked for potential explosives.
When asked about the report that the shooting may have been sparked by a dispute at a party behind held in a conference room in the building, Burguan said he had no confirmation that the people who left after the dispute returned or that they were the assailants.
A federal spokesman said potential links to terrorism were being investigated, although there was no clear indication that there were foreign terror links.
5:10 p.m. Wednesday
The Los Angeles Times reports the shooting that left 14 people dead and 17 others wounded may have happened after a dispute at the holiday party that was being held at the Inland Regional Center.
“A senior federal official who is monitoring the case said investigators believe one of the shooters left the party after getting into an argument and returned with one or two armed companions."
4:25 p.m. Wednesday
A neighborhood in San Bernardino is the scene of massive police activity. Residents are warned to stay inside.
4:03 p.m. Wednesday
Sgt. Vicki Cervantes said one suspect was still being sought, but she could not confirm the total number of suspects and said the information would be provided within the hour. Cervantes confirmed the pursuit of the dark SUV that ended in a crash and gunfire was related to the investigation of the late morning shooting in San Bernardino.
3:55 p.m. Wednesday
The number of injured is changed from 14 to 17. The number of fatalites remained at 14 in a mass shooting that began around 11 a.m. local time in the southern California city of San Bernardino.
3:30 p.m. Wednesday
The Sheriff's Office reported that all officers were OK, despite an earlier report that an officer may have been hit by gunfire.
3:20 p.m. Wednesday
Although a police pursuit that ended in massive gunfire was not confirmed to be connected to the earlier shooting in San Bernardino, a local reporter said there were two people in the black SUV involved in the pursuit, their condition unknown, and an officer was hit by gunfire, possibly ricochet gunfire.
3:15 p.m. Wednesday
Live video above the end of a police pursuit showed a black SUV with the windshield blown out by bullets. A suspect was seen on the ground, possibly deceased. A KABC helicopter report said there was a report that an officer may have been injured in gunfire. There was still no confirmation the pursuit was connected to the shooting nearly four hours earlier.
3:10 p.m. Wednesday
Local reporters said there was at least one and possibly two pursuits in progress and gunfire was being exchanged.
At least one pursuit suspect was reportedly in custody, but there was no confirmation the pursuit was in connection to the shooting.
3:05 p.m. Wednesday
Rep. Peter King (R), of the Senate Intelligence Committee, said there was no evidence so far that the shooter or shooters were connected to foreign terrorism.
2:45 p.m. Wednesday
Keith Nelson, V.P. of the Board of Trustees of the Inland Regional Center, told CNN that the group that was using the room where the shooting took place for a holiday event was from the San Bernardino County Dept. of Public Health.
1:55 p.m. Wednesday
At a news conference, authorities said as many as 14 people had died and as many as 14 others were injured in the shooting. Up to three suspects were being sought. It's believed they fled the scene in a dark SUV.
San Bernardino Police Chief Jarrod Burguan said it took hours to clear the building after the shooting was reported. The suspects have not been identified and no motive has been identifed, he said.
Burguan said most of the victims were located in the same area of the facility where the shooting happened, and that was the only active scene.
Burguan said he did not have any information indicating that children were involved. Burguan said the shooters had long guns, although he did not know what type.
San Bernardino Sheriff John McMahon said the courts and local city and county buildings were on lockdown, and hospitals and schools were implementing lockdowns or increased security measures, as well.
An FBI spokesman said it was not yet known if the shooting was a terrorist incident.
Burguan said it was at the very least domestic terorrism.
"They came prepared to do what they did, as if they were on a mission," Burguan said.
1:49 p.m. Wednesday
President Obama said he hoped the shooting would be contained and urged bipartisanship, saying, “What we do know is there are steps that we can take to make America safer.”
The Associated Press reported that there was still nobody in custody.
1:30 p.m. Wednesday
Marcos Aguilera says his wife was inside a social services facility in Southern California when gunfire erupted but she got out of the building unharmed.
He told KABC-TV that a shooter entered the building next to his wife's office and opened fire.
Aguilera says they locked themselves in her office and saw bodies on the floor. He says his wife saw ambulances taking people out of the building on stretchers.
Authorities say multiple people were shot and some were killed Wednesday at the Inland Regional Center in San Bernardino.
Police Sgt. Vicki Cervantes told KCBS-TV that police were searching for more than one gunman. She didn't have specific numbers on the number of dead and injured.
Original post: Officials in California have confirmed that there is an active shooting situation with multiple casualties in San Bernardino, California.
Fox 11 in Los Angeles reported that police are looking for up to three men, dressed in military gear, perhaps wearing body armor. They apparently were driving a dark SUV.
There are reports that the armed suspects were using rifles.
The shooting happened inside the Inland Regional Center.
Police confirm that people have died, The Associated Press reported.
San Bernardino police Sgt. Vicki Cervantes told KCBS-TV on Wednesday that "there are multiple casualties and there are some confirmed fatalities." She says she doesn't have specific numbers.
According to the San Bernardino Sun, the Inland Regional Center provides services for developmentally disabled people.
The president and CEO of the Southern California social services center where gunfire has erupted says the focus is on a building that houses at least 25 employees as well as a library and conference center, The AP reported.
Marybeth Feild of the Inland Regional Center says "the incident is in the conference area" that an outside group was renting Wednesday. She says she is not at the center, which serves people with developmental disabilities and does not know what outside group rented the center, The AP reported.
Feild says people served by the center also would have been in the building.
The ATF and FBI are on scene.
Some people were seen being wheeled away on gurneys, while others walked quickly from a building with their hands in the air. They were searched by police before being reunited with loved ones, The AP reported.
President Barack Obama has been brought up to date on the shooting at a Southern California social services center.
The White House says he was briefed by his homeland security adviser, Lisa Monaco, and has asked to be kept informed as the situation develops, The AP reported.