The shooting happened early Wednesday afternoon at the Valero station on the 10000 block of Tidwell Street near Brock Park.
According to authorities, the men began arguing inside the gas station's convenience store. After the argument escalated, one of the men went to his car to retrieve a gun, and gunfire erupted.
One victim was shot in the head, transported to Lyndon B. Johnson General Hospital and pronounced dead. The second victim was shot in the leg and taken to Ben Taub Hospital.
Police do not know if the man shot in the leg ever fired a weapon. That person's companion left the scene in a brown car, and investigators are looking into whether or not somebody in that car fired shots.
During the shooting, one of the convenience store's windows was shot out.
Anybody who witnessed the altercation is asked to contact the Houston Police Department.
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