INDIANAPOLIS (AP) -- Survivors of a deadly explosion that devastated an Indianapolis neighborhood are trying to rebuild their lives even as they await answers about what caused the massive blast.
Investigators are focusing on natural gas-fueled appliances as they search for the cause of Saturday's explosion, which killed two people, leveled two homes and left dozens more uninhabitable.
Indianapolis Homeland Security Director Gary Coons said Tuesday that his "investigators believe natural gas is involved" and were "recovering the appliances from destroyed homes to help determine the cause." He made the announcement after the National Transportation Safety Board said investigators had found no leaks in the gas main or pipes leading into the house that exploded.
"Based on the NTSB statement, our focus is on the houses and appliances," Coons said in a statement.
Some residents expressed frustration at the pace of the investigation Tuesday night during a meeting of about 150 residents of the Richmond Hill subdivision held at a church near the damaged neighborhood. But 51-year-old Helen Upton, who attended the meeting, said she and most of her neighbors are willing to wait while officials sort through the evidence to pinpoint the cause and source of the suspected gas explosion.
"It's only been three days and there's a lot of debris and rubble where that house blew up, so I'm not surprised they're still being tight-lipped," she said. "But I think some of the neighbors are obviously getting anxious. There's just a lot of questions and a lot of 'we don't know yets.'"
Upton said she was at home sleeping while her ex-husband was visiting with their two children when a house about 50 to 60 yards away exploded. The blast nearly tossed her off her bed, she said, and shattered her home's front windows, blew off its front door and buckled her garage door.
Three days after the blast, Upton said, her household is "fully functioning" again and she's thankful none of her family were injured. But she said her home still has some boarded up windows and other needed repairs and her kids' nerves are frazzled.
"My kids are having trouble sleeping. They're afraid there could be another explosion since we don't know what it was," said Upton, who works at Indiana Farm Bureau.
An owner of the house believed to be at the center of the explosion has said the home's furnace had been having problems, but his estranged wife, Monserrate Shirley, said the furnace was fine.
Shirley was living at the home but was not there when the explosion happened. She told The Associated Press that the thermostat was replaced recently, correcting a problem heating the home. She also said she smelled a strange odor outside before the blast, but didn't know if it was connected to natural gas.
The natural gas lines inside the house would be under the oversight of the utility or the state, said NTSB spokesman Keith Holloway.
Citizens Energy spokeswoman Sarah Holsapple said the utility had found no leaks in its underground facilities in the neighborhood.
Gas and explosion experts say the blast has some unusual characteristics to have been caused by a faulty appliance.
"One hell of a lot of gas had to be leaking out ... and that's typically not symptomatic of a furnace problem," said Sergei Traycoff, president of Bolls Heating and Cooling in Indianapolis. "I've never heard of one causing this big a blast."
More than a dozen home explosions linked to natural gas have occurred in the last two years. Many involved a single home, though more devastating blasts tied to pipelines have been reported — including a 2011 explosion in Allentown, Pa., that killed five people and a blast in 2010 in San Bruno, Calif., that killed eight people and destroyed 38 homes. A gas leak in a Colorado home last month sparked an explosion that sent five people to a hospital and damaged several homes.
John Erickson, vice president of the American Public Gas Association, said more gas blasts are caused by appliances than by pipelines, but even those are rare. Technological advances such as microprocessors and the switch from pilot lights to electronic ignitions have made appliances safer, he said. Gas companies have been required since 1970 to add a chemical that smells like rotten eggs to the odorless gas to make leaks easier to detect.
Erickson said it was odd that the blast apparently flattened two homes side by side. Generally, if a house explodes, it will knock out the wall of the home next door, but not level it, he said.
Glenn Olvey, 52, lived in a home that was heavily damaged. The blast hurled Olvey several feet and trapped him, his wife and one of their two teenage daughters when their roof collapsed. Rescuers pulled them from the debris as flames shot across the roof.
Olvey said the explosion nearly tore his house in half.
"I have been through car accidents, I've been through motorcycle accidents, I've been through tornadoes. I have never, never had anything like that," he said.
The house can't be salvaged, and the family isn't being allowed to return for their belongings. But Olvey said everything, including his awards from 30 years as a softball umpire, is replaceable.
Olvey said he and his wife, Gloria, have struggled knowing that the explosion killed Jennifer and John Longworth, just two doors down.
"We know that if the blast had gone the other way, it could have very well been us," he said.
Meanwhile, Traycoff, the heating company owner, said the explosion "raises a red flag" for homeowners who could be behind in their annual furnace inspections.
"If anyone hasn't had it done in a while, they would want to have it inspected," he said.