Officials say the armed suspect went into Frozen World on Yosemite Avenue Wednesday night.
He demanded cash from the cashier and pulled out a gun, police said.
The employee gave him the money, and he ran out of the store.
In a photo captured by surveillance video, the suspect is wearing a dark hooded sweatshirt and medical face mask.
Anyone who can identify the suspect or knows his whereabouts is asked to call the Merced Police Department.