CHICAGO (CBS) -- Hoosiers in the South Bend, Indiana, area are still reeling after a shooting at a shopping mall left a 22-year-old man dead.

Witnesses say two men got into a heated argument at University Park Mall Saturday around 3 p.m. Then one of them pulled out a gun and shot the other, sending shoppers running.

"We heard multiple gunshots and we had two customers with us, so we rushed them to the back. And we just went to our bathroom and locked the door. We did hear the shooter next door at Francesca's banging. He was saying, 'Open the store,'" said witness Alivia Brissette.

Police quickly got on scene, got everyone out safely and secured the mall, which was closed for the rest of the day. It was not clear if it would reopen Sunday morning.

Police said the shooting was an isolated incident after an argument between the two men.

They are still looking for the gunman.