It happened around 3:45 a.m. in the 9300 block of Richmond Avenue at a shopping center.
The shooting victim had just left the Castle Lounge with friends when an argument began among the group before guns were drawn, according to Houston police.
When two security guards approached and told them to drop their weapons, the victim pointed his gun toward one of the guards, police said. The guard fired his gun and hit the victim multiple times.
The victim, a man in his 20s, was pronounced dead at the scene.
The security guard was detained, police said, but it wasn't clear if any charges were expected.
There was no word on the victim's identity.