UPDATED | November 1 2015 3:01 PM

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DALLAS (CBSDFW.COM) — A 21-year-old was shot and killed after he was trying to buy marijuana at a gas station Friday night, police say.

Officers said they found the victim dead when they responded to the shooting around 11:45 p.m. at the intersection of Dolphin Road and Military Parkway. According to police, David Len McGary was trying to buy marijuana from an unknown man, possibly 20 to 25-year-old, in the Texaco gas station parking lot before he was shot.

Dallas police are still investigating.

Police say the McGary and the suspect had gotten into an altercation, with several witnesses around, which led to the suspect pulling out a handgun.

Police say McGary was running away from the gunman when he was shot. He had collapsed on nearby Beall Street. The shooter fled the scene.

Dallas Fire Rescue placed McGary in the ambulance but did not transport him because he had died at the scene.

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