The 12 August blast in Plum, a Pittsburgh suburb, left three others injured, including one person in critical condition, according to BBC.
Three other structures in the neighbourhood were destroyed and at least a dozen others damaged, but reports emerged that investigators have begun working to determine the cause of the blast.
According to officials in Pennsylvania’s Allegheny County, they received an emergency 911 call at about 10:30 (15:30 BST) local time on Saturday. Police and firefighters “arrived on scene and reported that there were people trapped under debris”.
“It appeared as if one house had exploded, and two others were engulfed in fire. Multiple other homes were damaged with windows blown out,” they said in a Facebook post.
Doorbell camera footage – which has not been independently verified by the BBC – shows a massive explosion sending smoke and debris into the sky above the neighbourhood.
BBC reported that five bodies were later recovered from the scene.
Officials say it is still unclear who was home and if any visitors were in the area at the time, complicating efforts to identify the dead.
“ID is expected to take some time as it will involve the use of dental records, and potentially DNA, for formal identification,” Allegheny County said on X, the social media network formerly known as Twitter.
While officials have not publicly named any of the victims, family members identified Casey Clontz, 38, and his son, Keegan, 12, as being among the five killed.
Mr Clontz and his son lived four houses away from the scene of the explosion. It is unclear why they were there, although family members told local news outlet TribLive that they were likely visiting neighbours.
A statement from the Clontz family described Keegan as Casey’s “shadow”, and the pair often went fishing and hunting together.
“Keegan and Casey were their most happy when they were spending time at the lake with their lake family and friends. They swam, did boating and loved cruising around in their golf cart,” the family said.
Keegan was part of a youth football programme and was due to start junior high in a week.
Casey and Jen, his wife of 14 years, also had a 10-year-old daughter, Addie.
Additionally, an online fundraiser has been set up for the Oravitz family, which owned the property where the explosion took place. It is unclear if any members of the family are among the dead.
Crews from at least 18 local fire departments were needed to douse the flames. More than 50 firefighters were treated at the scene for minor issues, primarily heat exhaustion.
Local police and fire officials are investigating the cause of the explosion alongside staff from the local utility company and state public utilities commission.
Officials told CBS, the BBC’s US partner, that the probe will be a “slow and long process” that could potentially take months, even years, to complete.
One resident, Rafal Kolankowski, told the Pittsburgh Post-Gazette that the explosion shattered windows in his house and knocked him and his wife down.
“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,” Mr Kolankowski was quoted as saying.
“I was just with some of the neighbors yesterday, right, and now this happens.”
