Austin, TX – A build-up of natural gas caused a house in south Austin to explode and seriously injure two people inside, according to the Austin Fire Department.

The massive explosion happened Saturday afternoon at a house at 2301 Bendridge Trail, which is just off William Cannon between Interstate 35 and South Pleasant Valley Road.

Firefighters put out a gas line fire started by the explosion when they first arrived. The home, though, was destroyed.

Santana Vazquez lives across the street and witnessed the blast. He said it caused the ground to shake.

“All of a sudden we heard the explosion,” Vazquez said, “and then I looked around this way and saw the roof of the house up in the air.”

The force of the explosion sent debris flying into other people’s yards and houses nearby. It also caused extensive damage to the house next door, displacing Diego Rocha’s father and brother.

“I think they’re just happy,” Rocha said about his family members. “They see the bigger picture. Forget materialistic stuff. It’s a blessing. Accidents happen.”

Firefighters said a man in his 50s and a woman in her 40s were badly burned during the explosion. A neighbor told KXAN that he ran into the splintered home right after the explosion and got the man out safely. The woman had already made it out to the front yard, the neighbor said.

According to Austin-Travis County EMS, the man was taken to Dell Seton Medical Center, while the woman went to another hospital. Firefighters said they were in serious condition Saturday night, but first responders expect them to recover.

The Austin Fire Department said at least five other homes and several cars were damaged during the explosion. Firefighters are estimating the damage to cost about $750,000.

Austin firefighters and crews from the Texas Gas Service are investigating how the build-up of natural gas happened.