Security guard shot during robbery at Kevin's Hamburger Heaven in Bridgeport

CHICAGO (WLS) -- A security guard was shot during a robbery at a 24-hour restaurant on the South Side. A search is underway for the two suspects.

Kevin's Hamburger Heaven in the 500-block of West Pershing Road in the city's Bridgeport neighborhood was packed with customers when two men walked in around 3:10 a.m. Friday - one armed with a handgun - and demanded money, police said.

Police said one of the suspects shot a security guard who got in a fight with the pair when he tried to intervene. The 36-year-old guard suffered a graze wound to the backside and was taken to Stroger Hospital, where he is listed in good condition, police said.

When the security guard was injured, people ran into the bathroom to take cover, witnesses said.

"I didn't see anything. All I heard was somebody say they're robbing the place. The people I was with, running to the bathroom. I ran into the bathroom. I didn't see anybody. I didn't see anything. I ran into the bathroom. That was it," a witness said.

The suspects drove away with the whole cash register, which contained an undetermined amount of money, police said. Police have not yet released a description of the suspects nor the vehicle.

No other staff members or customers were hurt.

Three people were shot - two fatally - outside the same restaurant in January 2013. Regular patrons of the restaurant said incidents like these do not happen often.

"I wish it wasn't like that, but I don't really worry when I come down here. I don't think it happens too much. When it happens, one time is enough. But I don't think it happens a lot," D.J. Jones said.

Police were able to examine surveillance footage in that case. There is no word yet on whether there is surveillance video of the shooting early Friday morning.