Police in the Southern California city of San Bernardino are responding to reports of an active shooter at a social services facility.
Police say there are reports of multiple victims.
Triage units are being set up in the area, and some people have been seen being wheeled away on gurneys. Others walked holding their hands in their air are being led away by authorities.
No arrests have been made.
San Bernardino is about 60 miles east of Los Angeles.