Police say he handed the teller a note, which read something similar to, "I have a gun. Don't do anything stupid. Give me the money."
The teller handed the suspect cash and the suspect took off on foot. The incident occurred on Feb. 1.
The suspect is described as a black man in his 40s, about 5 feet 7 inches tall and weighing about 180 pounds. He is described as bald and was last seen wearing glasses, a black leather jacket, a white button-up shirt and dark pants.
If you have any information that can help investigators, you're urged to call (951) 353-7137.
Authorities believe the same suspect may be responsible for similar robberies in Riverside dating back to last November.