A man used a gun to rob a convenience store at 9 tonight near 23rd and Iowa streets.

Clerk Matthew Downing, of Presto Convenience Store, 2330 Iowa, said the man pointed what looked like a single-barrel shotgun at his head and demanded money.

A customer in the store was forced onto the ground. But no one was injured.

Downing said the man took about $400 and ran away to the south. He described the man as a 20-year-old light-skinned black male, who was about 5 feet 5 inches tall. He wore a white shirt with baggy jeans and a blue handkerchief over his face.

Another man was the apparent lookout and ran to the north after the robbery, Downing said.

Police are investigating the robbery, which has forced the 24-hour store and gas station to close.