MANOR — Three people suffered severe burns and at least one was critically injured after authorities said a propane tank exploded outside a home in Manor, officials said Thursday night.

Medics, firefighters and police officers responded around 7:16 p.m. to reports of an explosion at the 11400 block of Austex Acres Lane, Austin-Travis County EMS said in a tweet.

Three residents — two men and a woman in their 40s — were inside of the home when authorities believe the tank exploded, said ESD No. 12 Chief Ryan Smith.

Smith said a gas line that ran from the propane tank through the home was leaking. When residents lit a heat source like the stove or a cigarette, the home exploded.

"Somehow a valve got hit open," Smith said.

All three residents walked outside of the home after receiving serious burns to their faces and extremities. Smith Friday said about 40% of each person’s body had first and second-degree burns.

Medics arrived shortly after and took one of the three patients in an ambulance. The two others were transported by helicopter, medics said. The three victims were taken to Dell Seton Medical Center with critical life-threatening injuries, EMS said.

Firefighters had initially reported several houses had been affected, but Smith said only one home was damaged.

The 1,000 square foot home was a total loss, Smith said.

Authorities closed off several blocks while they responded to the call, leaving a group of people temporarily unable to go back to their homes.

Luis Torres, who lives in the neighborhood, said he had been waiting to get back home about half an hour. Torres said he was out walking when the explosion happened but he didn’t see or hear anything unusual. He first noticed something was going on when several dogs in a house started barking.

"I was just passing by when I heard police approaching. A lot of emergency vehicles and helicopters started getting there," he said.

Roads had reopened by 10:15 p.m.