Officers went to the "Kwik Shop" at 36th and Leavenworth Streets early Frday on a robbery call.
A clerk told them a man approached the counter, displayed a firearm, and demanded cash.
After getting an undetermined amount of cash, the bandit ran from the store on foot westbound.
Police say he was wearing a blue hooded sweatshirt and white bandana.
The investigation continues.
Anyone with information is urged to contact "Omaha Crime Stoppers" at (402) 444-STOP, at www.omahacrimestoppers.org or on the P3 Tips mobile app.