Police say three men shut off the power at an East Side restaurant then roughed up the cook and robbed a customer.
Officers responded to a call for robbery around 12:45 a.m. Monday at the Sonic in the 5000 block of Rigsby near Loop 410.
Investigators said the suspects turned off an electrical box in the back of the restaurant and forced their way inside while an employee went to check on the problem.
Police said a cook began to fight with one of the suspects and was struck by a gun.
The suspects then ordered employees to open the safe, but they were unable to, so the men stole a cell phone from a customer and fled on foot.
The suspects will face aggravated assault and aggravated robbery charges if caught. Police did not have clear description of the suspects and said they were all wearing hooded sweatshirts.