BRENTWOOD, N.Y. (August 15, 2012)--A propane explosion destroyed a suburban New York house, killing a toddler and injuring 17 other people, police said Wednesday.

Officials say they are still trying to determine what ignited the gas.

Suffolk County authorities returned to the scene Wednesday in the middle-class neighborhood of Brentwood on Long Island.

Police confirmed Wednesday that preliminary suspicions that propane was the cause.

Two 200-pound propane gas tanks were on the premises, but no natural gas lines were present.

The explosion Tuesday reduced the entire structure to small shards of wood, plywood, drywall, insulation and other materials.

The 18-month-old boy's parents were among four other residents who were injured.

A plumber and insurance company representative visiting the home, seven police officers, two firefighters and two neighbors also were hurt.