The incident was first reported just before 12 p.m. Wednesday on the 400 block of Hibernia Road.
Firefighters and EMS responded to the home and found the victims suffering from burn injuries.
Chopper 6 Video over the scene:
Officials said one adult and two children were flown from the scene by medical helicopter to an area hospital. Two others were taken to a hospital by ambulance, and one person refused treatment.
Linsey Carpenter, who lives nearby, said she heard the explosion and went to help.
"We saw the little girl run across the street. We grabbed her and checked her out. Her hair was singed, her eyebrows were singed. Then the little boy came out and that's when the flames started," she said.
“Her hair was singed. Her eyebrows were singed.”- one of the many good samaritans steps in to help some of the youngest victims of the house explosion @6abc https://t.co/Fa2ELOExVz pic.twitter.com/Cl2TnhH37a— Christie Ileto (@Christie_Ileto) July 21, 2021
Carpenter, who is a nurse, gave immediate aid to both the little girl and boy before firefighters and medics arrived on scene.
"Then, the grandmother came out and she was visibly upset," Carpenter said.
Like many of Joe Formica's neighbors, he felt the impact of the home exploding doors down. He raced to Lafeyette and Hibernia to see the farmhouse at the corner engulfed in a four-alarm fire.
"Just billows of smoke and large flames shooting out everywhere," he said.
Nearly 60,000 gallons of water had to be brought in to douse the flames, according to Chief Todd Ziegler, of the Wagontown Fire Company.
"We had to bring in the tankers to support our water supply operation. Currently, we are drafting out of a pool and we're currently drafting out a pond on the property," he said.
Officials said the home, which does have an outside propane tank, was secured as firefighters continued to work.
Several state, local and federal agencies remained on scene and were working to determine the cause of the explosion.