Gas station clerk Silvia Perez was cleaning up for the evening when a man in a white surgical mask entered the Shell Station at 899 Airport Blvd. with a gun.
"I stopped right by the register and saw him coming up with the mask on," Perez said. "It was very scary."
Perez said business had slowed by around 8:45 p.m. Monday night.
She had cleaned a drink machine near the back of the store, Perez said, and was walking back to the register where she saw the man approaching the door of the food mart wearing a white mask. He held.
The robber then cornered Perez behind the register, pointed the gun toward her chest and told her to open the register. The suspect removed the money from the register and then demanded that Perez empty her wallet.
"He asked where there was more money," Perez said. "He grabbed my wallet and I told him, 'Don't touch my wallet. There's nothing in there.'"
Perez, who was back at work Tuesday, said the robber fled the store and warned her not to call the police before running out.
Perez immediately called police to report the crime.
The suspect wore a red and black beanie, dark-green puffy coat, dark jeans and white tennis shoes, according to police. He was described as a heavyset black man between 25 and 30 years in age.
The South San Francisco Police Department is currently searching for the robber. Anyone with information on the robbery should call police at 650-877-8900.
Bay City News contributed to this story.