A Mandan convenience store was robbed by an armed man, police say.

Lt. Paul Leingang said the man brandished a gun and locked the store's clerk inside a bathroom at about 12:30 a.m. Thursday.

The clerk wasn't injured, police said.

Leingang said the suspect was wearing dark clothing and a ski mask. He said detectives are going over the surveillance video to get a better description.

Police also are looking for a potential witness, who was at store just before the robbery, Leingang said.