Detectives say a man went into an AM/PM on Highway 140 near W Street just before 3 am Sunday.
The store clerk says the suspect pointed a gun at him, demanded cash and ran away with the money.
Surveillance footage shows the robber wearing a black hooded sweatshirt and a mask.
No other details are known at this time.
If you have any information on this armed robbery, you are asked to contact Merced Police.