The would-robber who was killed was 16 years old, and his accomplices may be around the same age. Chicago police are investigating whether the three are connected to a series of similar robberies.
On Tuesday night, friends of the alleged robber who was killed left tokens of mourning at the gas station where police say the cook county sheriff's sergeant acted in self-defense...
"When you see that video, you're just stunned and just incredibly happy that he was not harmed," said Cook County Sheriff Tom Dart.
The video shows the off-duty sergeant filling up at a pump when three men approach him demanding valuables, one of them pointing a gun.
With his left hand, the sergeant appears to fumble in his pocket before pulling out his gun with his right hand and firing at the would-be robber, hitting him in the head. We've stopped the video before that moment.
"The way he responded was so amazing. It was almost out of a stop-action frame movie where he had his wits about him throughout as a gun is being put on him," said Dart.
The other two suspects run off as the 19-year sheriff's department veteran assumes a defense position.
The wounded robber, identified as 16-year-old Deonta Mackey is still moving, apparently looking for his gun as the sergeant kicks it away from reach.
Moments later, Mackey would die at the scene. His alleged accomplices are still at large.
"If you know your sons hang with this young man, and you got an idea that those were the two that ran, turn those two individuals in because sooner or later, someone is going to come knocking at your door. Sooner or later, they're going to have an investigative alert," said Andrew Holmes, community activist.
Friends say Mackey was a junior at nearby Corliss High School and lived a short walk from the gas station in an apartment building.
Officials are investigating whether Mackey and the two other suspects are connected to a series of similar South Side robberies.
"You all seen the video footage. You know who they are. We know they stay in this area. They're very close. And we ask you to turn them in," said Holmes.
Employees at the gas station say Mackey was a regular in their convenience store, and again he lived just a few blocks away. Friends told Eyewitness News he played basketball at Corliss High School.