A security guard handling a bar dispute early Sunday morning was shot and killed by police in a suburb outside of Chicago.

According to local station WGN, Jemel Roberson asked several drunk patrons to leave Manny's Blue Room Bar on Sunday at around 4 a.m. Shortly after leaving, the group returned and someone opened fire in the bar. The 26-year-old guard returned fire and apprehended one of the men in the group, before local police arrived on the scene.  

Witnesses say Roberson, who is black, was holding down the suspect when a responding officer shot and killed him. "He had somebody on the ground with his knee in back, with his gun in his back like, 'Don’t move,'" Adam Harris told WGN. "Everybody was screaming out, 'Security!' He was a security guard...And they still did their job, and saw a black man with a gun, and basically killed him."

The Midlothian Police Department hasn’t released the name of the officer, but confirmed the shooting. "A Midlothian officer encountered a subject with a gun and was involved in an officer-involved shooting. The subject the officer shot was later pronounced deceased at an area hospital," Chief Daniel Delaney said in a statement.

Roberson planned on becoming a police officer one day, and performed at several Chicago-area churches playing keyboard and drums. His mother Beatrice filed a lawsuit on Monday morning, according to TMZ, against Midlothian and the officer. A GoFundMe page has been set up to help Beatrice and Roberson’s family cover funeral costs.

The Cook County Sheriff's Office has opened an investigation into the shooting.