A robber threatened a gas station clerk with a knife and demanded money at 3:30 a.m. Saturday.

Police said the clerk was making coffee when a man carrying a knife with a scarf partially covering his face entered the store, located at 2641 W. Monroe St.

The robber ran toward the clerk with a knife, which had a 6-inch blade, and pushed him to the ground and demanded money from the register.

The clerk complied and handed the robber an undisclosed amount of money. The robber also demanded money from a second register, but the clerk couldn’t open it, police said the robber fled out of the store northbound.

He was described as a black man, about 6 feet 3 inches tall, 250 pounds, wearing a heavy black coat and grey sweatpants. The scarf covering his face was a light color, police said.