One officer was injured in the gun battle but does not have life-threatening injuries.
San Bernardino, California, police Chief Jarrod Burguan said the dead suspects are male and female. They were dressed in "assault style" clothing, according to Burguan, and had assault rifles and pistols.
Burguan said the shootout happened after officers went to a home based on tips and saw a black SUV with the suspects inside leave the property. Law enforcement officers have surrounded the home in Redlands, California. It wasn't clear if anyone was inside.
Police said up to 14 people were killed and up to 17 others were wounded when multiple gunmen believed to be armed with rifles and wearing body armor opened fire at a Los Angeles-area social services facility on Wednesday.
Police said an explosive device was found at the Inland Regional Center in San Bernardino and they were working to remove it. Burguan said a third person seen running from the scene of the shootout is in custody, but he said it is unclear if the person was involved.
The situation remains very fluid and an active manhunt continues in Southern California. The FBI says it's a possibility that the shooting is "terrorism."
Chief Burguan said the number of people killed and wounded were preliminary estimates that could change. Ten of the wounded were hospitalized in critical condition, and three were in serious condition, San Bernardino Fire Chief Tom Hannemann said.
"They came prepared to do what they did, as if they were on a mission," Burguan said, noting the shooters carried long guns, not handguns.
The Inland Regional Center is a nonprofit that works with individuals with developmental disabilities. In what authorities described as a carefully planned assault, the gunmen invaded the building and began shooting around 11 a.m. They opened fire in a conference area that the San Bernardino County Department of Public Health had rented out for a banquet, said Marybeth Feild, president and CEO of the center.
PHOTOS: Scene of mass shooting at San Bernardino social services facility
Inland Regional Center employee Brandon Hunt told Eyewitness News the shooting took place in the building with the facility's main auditorium, where a holiday party of some sort was being held. He said the auditorium is regularly rented out to outside agencies. Hunt said approximately 550 people typically work at the facility at any given day. That the violence happened at a place dedicated to helping people with developmental disabilities made it even harder for some to comprehend.
"These are all disabled kids, very disabled," said Sherry Esquerra, who was searching for her daughter and son-in-law, both of whom work at the center. "She gets all the services she possibly could for these kids. So I just don't understand why somebody would come in and start shooting."
MORE: What we know about the Inland Regional Center in San Bernardino
Investigators were searching the building room-to-room and have yet to clear it. Burguan said he couldn't confirm a report in the Los Angeles Times that someone left the party and came back with guns. He said someone did leave, but it wasn't clear if that was the person who came back and started shooting. Burguan cautioned that it was very early in the investigation.
Marcos Aguilera's wife was in the building when the gunfire erupted. He said a shooter entered the building next to his wife's office and opened fire.
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"They locked themselves in her office. They seen bodies on the floor," Aguilera said, adding that his wife saw ambulances taking people out of the building on stretchers.
Aguilera said his wife was able to get out of the building unharmed.
Terry Pettit said he received a text message from his daughter, telling him that gunmen were in her building and that she and some co-workers were hiding. She said there were 10 to 20 people were shot.
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The Associated Press contributed to this report.