It happened around 11 p.m. Sunday at the store on Illinois Avenue in Oak Cliff.
Police said two unknown black suspects walked in just before closing and demanded money. A third suspect waiting outside acted as a lookout.
The employees cooperated, but the armed robbers still shot one worker numerous times in the chest.
Family members said 28-year-old Leonardo Ortega died at the hospital.
One of Ortega's uncle's says he despised violence and often talked of what life could be in a world without violence, so it's especially painful that he came to such a tragic end.
Another female employee was uninjured.
The robbers, possibly in their 20s, stole an undetermined amount of money and fled the scene.
Dallas police have released surveillance video from a nearby business. Police say it shows the robbers walking past the camera.
The surveillance video doesn't show faces. Police say the robbers wore hoodies.
Crime Stoppers is asking for the public's assistance in identifying these suspects.
Anyone with information that leads to the arrest and indictment of these suspects will be awarded up to $5,000. Additionally, Oak Farms Dairy will pay $10,000 for information leading to an arrest.
Anyone with information can call Crime Stoppers at 214-373-8477.
FOX 4 is on YouTube -- http://bit.ly/fox4subscribe