INDIANAPOLIS - Investigators working to determine a cause of the south side Indianapolis explosion have narrowed in on natural gas.

Gary Coons, chief of the Indianapolis Department of Homeland Security, confirmed Tuesday that the investigation was focused on natural gas.

"Our investigators believe natural gas is involved," Coons said. "They are currently in the process of recovering the appliances from destroyed homes to help determine the cause. Based on the NTSB statement , our focus is on the houses and appliances."

Citizens Energy Group officials said inspectors found no problems with gas lines in the neighborhood or the gas lines running to individual houses, but that doesn't mean there were no gas issues inside the homes.

Two people were killed and dozens of homes sustained serious damage in the Saturday night blast that displaced 200 people.