Police are searching for the masked men who stormed a Denny's near Memorial Park, demanded money from customers and shot two people inside.
It was a "take-over type fashion" robbery, Houston police said.
Investigators told Local 2 three men with masks covering their faces stormed into the Denny's on Washington near I-10 and started shooting.
The suspects got away with cash from the registers.
Witnesses said there were about 15 customers inside at the time and the gunmen stole from them as well.
"They robbed a lot of people as they were shooting at the same time," said customer Luigi Major. "But from my understanding, they were after the purses, cell phones and at the same time they were pointing guns at the small kids."
According to Houston police detective Ken Nealy, one customer and one employee were injured in the shooting. The two victims were rushed to the hospital for surgery.
Police said the customer died from his injuries at Memorial Hermann Hospital. The victim's family identified him as Greig Placette, 64.
"He saved my life. He is my hero," said Placette's friend, Jonathan Ochoa, who was also in the restaurant.
He said Placette told him to hit the floor when the gunmen walked into the restaurant. He believes Placette saved his life and another as he put himself between the gunmen and a child.
Ochoa said "They intentionally went in there to kill people because they had no hesitation to shoot people. And most people were freezing up and couldn't even give them phones or wallets and they were actually coming on people and grabbing their stuff."
According to Ochoa, Placette was shot in the shoulder and lost a lot of blood.
He told Local 2, "Immediately I knew Greig wasn't next to me and basically just started praying because there were probably 20 shells that hit the ground and I just figured they were going and killing everyone."
The restaurant employee, a 43-year-old man, is being treated at Ben Taub General Hospital and is listed in stable condition.
Meanwhile, the searching continues for a total of four men.
Officials said a fourth suspect was outside during the robbery waiting in a minivan.
Denny's released the following statement to Local 2 Tuesday morning:
"We are very saddened by recent news at our Houston restaurant and our condolences go out to the victims of this senseless tragedy. We are assisting law enforcement in any way we can with their ongoing investigation and ask that any further questions be directed to the local authorities."
Anyone with information in this shooting is urged to call the HPD Homicide Division at 713-308-3600 or Crime Stoppers at 713-222-TIPS.