Some people flagged-down police while the shooting was happening at that store at 11285 Southwest Freeway around 10:15 p.m. Tuesday night.
When officers went inside the store, they found one man, believed to be 25 to 35 years old, was found already dead with gunshot wounds.
Police said a short time later, two men who they believe were involved in the shooting arrived at a local hospital with gunshot wounds. One is listed in stable condition in the hospital as of Wednesday morning. The third man, a 31-year-old, is listed in critical condition.
Officers said that they saw drugs in plain view where the shooting took place.
Detectives also have video footage of the events outside the store during the shooting, but not inside.
Anyone with information in this case is urged to contact the HPD Homicide Division at 713-308-3600 or speak anonymously with Crime Stoppers at 713-222-TIPS.