SAN DIEGO — San Diego County sheriff’s deputies are investigating a takeover-style armed robbery of an illegal marijuana dispensary.

Sgt. Kotaro Murashige says the Thursday night robbery in Spring Valley was reported by a passer-by, not by the staff of the business.

The two robbers forced their way in, disarmed a security guard and ordered employees to the ground.

The robbers fled with marijuana products but it’s not known if any cash was taken.

The Sheriff’s Department says the area has seen a trend of similar dispensary robberies in which armed guards were not a deterrent and staff members did not call for help.

The department says in some cases dispensary workers have refused to allow law enforcement to enter.