Police say the man went into the store on Main Street with a knife and demanded money. After the staff gave him money, he left.
Police searched nearby neighborhoods but couldn't find him.
Here's a description: White man, late 20s to early 30s, about 6' tall with a thin build. He was wearing a dark gray sweatshirt, light-colored pants and white tennis shoes. He had a camouflage mask covering his nose and mouth.
Anyone with information is asked to call Fox Valley Metro Police at (920) 788-7505.