Work was being done on the duplex's water line when the gas line was struck, causing the Nov. 12 explosion, Fairborn Fire Marshal Carl Day said.
A 13-year-old was transferred in critical condition to Shriner's Hospital for Children, one of about four hospitals in the country specializing in pediatric burns, said spokeswoman Louise Holker. Two men also were injured. Their conditions were not given.
The 1-year-old baby was in fair condition and a 5-year-old was in good condition on Nov. 13, a spokesman for Dayton Children's Medical Center said. A third child, whose age wasn't available, was treated and released Nov. 12.
The blast was one of three in the Midwest in recent days. Another in Benton Township in southwestern Michigan killed two people on Nov. 12 and injured four others. Its cause wasn't immediately known, but relatives said several oxygen tanks were inside. An explosion in Chicago on Nov. 13 flattened one home, scorched others and sent two people to the hospital with serious burns. Fire officials and utilities were investigating.
A woman who lived about 100 yards from the Ohio home that exploded, Cybil Poole, told the Dayton Daily News that the blast felt like a car hitting it. She said she saw the infant lying in the yard and that some of the other victims were still on fire.
A spokeswoman for Vectren Corp., said it hasn't been confirmed that there was a gas leak and the company would likely conduct its own investigation into the cause of the explosion.