Authorities tell Action News that two men, one armed with a sawed off shotgun, entered the Midtown II Restaurant located at 122 South 11th Street around 6:15 a.m. Sunday.
They demanded money from the manager, but quickly fled the diner before getting away with any cash.
Police believe the men forced the employees into the basement before they left.
No injuries have been reported.
Anyone with information is asked to call police.