Police received a report about the robbery at 9:46 p.m. The clerk said the man came into the store at the gas station, selected an item, pointed a gun at the clerk and demanded she open the register.
The robber took cash from the register and fled toward the In-N-Out Burger restaurant. Police and the Sonoma County Sheriff's Department's helicopter searched the area but did not find the suspect.
Police said the robber is a white male, between 19 and 22 years old with a thin build.