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Friends tell me 16-year-old Deonta Mackey was a sophomore at Corliss High School just a block away from here.

Last night, Mackey and two others tried to rob a man, who turned out to be an armed off duty Cook County Sheriff’s Officer.

A security camera caught it all. The off duty Cook County Sergeant, getting gas last night when three people come up, one shows a gun.

The sergeant puts his hands up, hands over his wallet then reaches for his own gun and fires.

16-year-old Deonta Mackey was shot in the head. The two other suspects took off.

“Whenever you got a gun you, you fear for your life.” Jesse Huscon, a gas station customer, says the off duty sergeant did the right thing.

“By him being a police officer or an officer of the law. You know, he has a right to stop the crime. He gave up his wallet like he was supposed to like anybody else was supposed to do cause you don’t want to lose your life.”

“He was cool with everybody, friendly person,” says Brandon Wade. Friends of Mackey, a sophomore at nearby Corliss High School, say he got caught up in the wrong crowd.

Wade says, “I’m saying he shouldn’t have did what he did to end up in this situation but its crazy man.”

Chicago police and the Illinois state police are investigating the incident. The sergeant’s name isn’t being released. Police are still looking for those two other people involved in the attempted robbery.