It happened around 2am at Club I.C.U. in the 9500 block of Mesa Drive near Rinn.
Police said two groups were at the bar, both celebrating birthdays, when a fight broke out between two women.
The fight spilled outside to the parking lot and grew in size. Suddenly, police said an unidentified man who had been inside the club pulled out a gun and fired several shots into the crowd.
"I come outside they started fighting," club owner Tommy Wyatt said. "We thought we had broke it up. The next thing I heard a gun fire."
Dozens of people ducked for cover but at least six were shot -- three men and three women.
Yvette McNeal was standing near the shooter when she saw the gun.
"A guy just got trigger happy," she said. "He wanted to shoot, play Rambo and started shooting."
According to police, 38-year-old Gilbert Kibble and 22-year-old Curtis Steward died at the scene.
Felipe Castillo, 26, was rushed to Ben Taub General Hospital where he died.
The three women were taken to area hospitals with gunshot wounds, but investigators said their injuries were not life-threatening.
According to officials, at least two of the victims were intentionally gunned down, and the others may have been hit by stray bullets.
All six victims were said by their families to be related. Now, their loved ones are preparing to plan funerals.
The killer remains on the loose. He is described only as a black male. Anyone with information that could help police solve this crime can call Crime Stoppers at 713-222-TIPS.