Channel 2 Action News is working on gathering more details about an altercation that police said forced them to shoot a gunman who opened fire inside of a bar.

DeKalb County investigators said it was just before midnight Saturday when an off-duty officer, who was working security at the Trebol Billiards Bar on Buford Highway, heard a commotion inside.

Channel 2 Action News crews arrived within minutes of the shooting, where police said stemmed from an argument that prompted an off-duty officer to call for back-up.

Investigators told Channel 2's Erica Byfield when the second officer arrived, one of the upset customers pulled out a gun and shot and wounded four patrons.

Eventually, police said one of the officers shot and killed the man with a gun.

One of the officers, who did not want to appear on camera, said they have a lot of work ahead of them to solve the case.

"There was a large crowd of people out here and a big crime scene, so we have to slowly take our time and methodically go through the crime scene and put the pieces of the puzzle together," the officer said.

Investigators have not released the names of any of the people involved in the shooting.

The condition of the customers in the shooting is still unknown.

Check back for updates.