4 people dead and 1 missing after explosion destroys 3 structures in western Pennsylvania

What caused a deadly house explosion? With 5 people now confirmed dead, there are growing questions about what caused a deadly explosion in a Pittsburgh suburb.

PLUM, Pa. — Four people were dead and a fifth was unaccounted for following a house explosion in western Pennsylvania that destroyed three structures and damaged at least a dozen others Saturday morning, authorities said.

Allegheny County officials said three people were taken to hospitals after the blast shortly before 10:30 a.m. in the borough of Plum, about 20 miles (32 kilometers) east of Pittsburgh.

Three people were transported to area hospitals, including one who was listed in critical condition and two who were treated and released. More than 20 firefighters were evaluated, many for heat exhaustion, authorities said.

The Allegheny County Medical Examiner's Office was expected to provide additional information about the deceased victims.

Emergency officials suspended operations Saturday night due to weather and concern for the safety of investigators. Crews were expected to resume working at the site on Sunday morning.

Emergency responders reported people trapped under debris after one house apparently exploded and two others were engulfed in flames, county spokesperson Amie Downs said.

Crews from at least 18 fire departments worked to douse the flames with the help of water tankers from Allegheny and Westmoreland counties, Downs said.

Officials told reporters at the scene they did not know exactly who was at home and who may have had visitors at the time of the explosion, so they could not provide an exact number of people considered missing.

The cause of the explosion is under investigation by Plum and county law enforcement and the county fire marshal's office. The state public utilities commission and local utilities also were at the scene.

George Emanuele, who lives three houses down from the home that exploded, told the Tribune-Review that he and a neighbor went to the home before the fire got out of control, where they found a man laying in the backyard and dragged him away from the scene.

Rafal Kolankowski, who lives a few houses away, told the Pittsburgh Post-Gazette that the explosion broke the windows in his house and knocked him and his wife to the ground.

After recovering and checking on his son, Kolankowski went outside and a woman told him another woman had been upstairs and a man was in the basement. The other woman later emerged covered in white ash, but the individual in the basement had not yet exited, he said.

"It's just tragic, I mean, it looks like a war zone -- it looks like a bomb hit our neighborhood and it's just unfortunate," Kolankowski said. "I was just with some of the neighbors yesterday, right, and now this happens."

Jeremy Rogers, who lives two doors down, told the paper he had been out shopping when he got an alert about a problem at his house and saw "all sorts of stuff flying around." His family was able to get out safely and he was allowed to go inside quickly to rescue his dog, although he could not locate the family's three cats.