INDIANAPOLIS (AP) — As investigators try to determine what caused a deadly explosion that ravaged an Indianapolis subdivision, an expert says people shouldn’t be alarmed by a homeowner’s suggestion that his faulty furnace could be to blame.

Investigators have been looking at gas meters and pipelines as they try to figure out what happened Saturday night when a blast killed two people, obliterated two homes and left dozens more uninhabitable.

John Shirley and his exwife own one of the homes leveled in the explosion. Shirley, 50, of Noblesville, said his daughter told him recently that the furnace had gone out in the house she shares with her mother and her mother’s boyfriend. He said his daughter told him the furnace was working again, but he wondered if a leak from the furnace could have led to the explosion that killed a couple next door. No one was in Shirley’s home at the time of the blast, he said.

Scott Davis, president and principal engineer of GexCon US, an explosion investigation firm in Bethesda, Md., said it’s hard to believe a furnace could cause the damage seen in the Indianapolis neighborhood. He noted that most furnaces have multiple safety switches that must be triggered before any gas is used.

“For a furnace to allow that much gas through, you’d have to defeat many of the safety features,” he said.

Public Safety Director Troy Riggs said investigators will treat the area as a crime scene until they rule out foul play. Local and federal investigators say it’s too soon to rule on a cause but are slowly weeding out some possibilities.

The National Transportation Safety Board sent investigators to check the integrity of a gas main and other lines serving the neighborhood, and local gas supplier Citizens Energy said it also was checking gas lines.

“It’s too early to speculate that this might have been caused by a gas leak,” Citizens Energy spokeswoman Sarah Holsapple said.