When firefighters arrived early Friday morning, HFD said 50-foot flames could be seen shooting from the house.
The property consists of a main house and a rear garage apartment. HFD Officer Ruy Lozano said firefighters found one of the bodies inside the home, a second inside the garage apartment and the third outside the home.
"The fire created a lot of popping like firecrackers. Like I thought it was a flat tire. A lot of noise," neighbor Rene Lozano said.
PHOTOS: House fire under investigation in NW Houston
The family lived in the house in Oak Forest, quietly, for nearly 30 years. That peace shattered forever when neighbors heard bullets and the house exploding as fire engulfed the home.
"It's sad and unfortunate," a neighbor said.
Police have identified the deceased as retired teacher Vicki Flanery, her husband David, and Charles Morton Acker.
"I'm at a loss for words. I can't believe," Tia Marias restaurant hostess Maria Elizondo said.
News of the murder-suicide shocked those who knew the couple, including employees at Tia Marias, the couple's favorite restaurant.
"They didn't seem like they were troubled. They were always nice. They seemed sweet to each other," Elizondo said.
ATF agents removed box after box of ammunition and a number of rifles from inside the home. Though the investigation is far from complete, they are not looking for any suspects outside of the home.