A woman was also shot in the leg. She was taken to Northwestern Memorial Hospital in serious to critical condition.
The shots were fired at an Aldi store near 90th and Halsted just before 8 o'clock when the store closes. At least one gunman, apparently intent on robbing the store, entered and opened fire. Witnesses heard a number of shots. One struck the male security guard in the head. Witnesses believe the suspect fled the store on foot.
Police are still looking for the gunman.
Many longtime customers are deeply upset.
"It's a shame. You try to make a few dollars, come to work, and people are trying to take your life. You don't have anything. We are all struggling out here," said Katherine Wiley, customer.
"I go to this store and I was going to stop in, and then when I seen all the action I said, maybe it's not a good time tonight," said Jerrie Loggins, customer.
ABC7 was told that security guards at the store generally carry guns. The gun that the victim was carrying is missing.