At least twelve people have been killed and at least 20 injured in a shooting that took place in San Bernardino, California, on Wednesday, Dec. 2.

The shooting occurred at the Inland Regional Center, a facility for people with developmental disabilities, according to CNN. It is unclear how many people were at the facility at the time of the shooting.

“As many as 30 hostages were seen coming out of the building, a center for treating developmentally disabled people, where the event occurred,” according to Fox News. “At least 12 fatalities occurred inside the building, which was surrounded by authorities, just before noon local time. The FBI and Bureau of Alcohol, Tobacco and Firearms were responding.”

The San Bernardino Police Department has confirmed one to three possible suspects involved in the shooting, according to the police department’s Twitter account.

The three suspects are believed to be armed with AK-47-type weapons, a local law enforcement official told CNN.

The suspects got into a black SUV and drove away, according to CNN.

Agencies in the area of San Bernardino have been advised to look for up to three men wearing some type of military gear who fled the shooting site, according to CNN.