New Chapel Hill, TX – Eroded pipes, a gas leak, cracks in the slab and a spark from the central heat and air unit were all factors in Tuesday’s fatal explosion and flash fire, officials believe.

Smith County Fire Marshal Jim Seaton said he and other fire marshals with his office sifted through the rubble of the home on County Road 2209 Wednesday and determined how the explosion occurred.Despite heroic efforts from a neighbor, who dragged her from the home, retired Chapel Hill High School teacher 76-year-old Molly Ferguson died as a result of burns and injuries she sustained.

The fire broke out shortly after 11 a.m. Tuesday, and Mrs. Ferguson was pronounced dead at East Texas Medical Center.

Seaton said the home was constructed on a concrete slab with a channel system in the slab for pipe carrying propane to appliances.

“When the home was first built there were two hot water heaters, the heating system and a propane- assisted fireplace,” he said. “Over the years, everything was converted to electricity except for the one water heater.”

Seaton said Mrs. Ferguson had propane delivered on Monday and the tank was filled.

“We believe that over the years, the acidity in the concrete may have caused erosion in the pipes, allowing the gas to leak into the channels and through cracks in her slab,” he said.

Glass shards, papers and other material were blown away from the house, and firefighters knew there had been some type of explosion which ignited the flash fire that quickly consumed the four-bedroom structure.

Seaton said propane gas is a heavy gas that does not rise until there is a buildup.

“There was no way anyone could have known this would happen,” he said. “The cracks in the slab were covered up with carpeting, and the gas just seeped up through it.”

Seaton said the gas in the channels flowed into an in-duct that lead to the central heating and air unit where he believes a spark from the air conditioning ignited the gas buildup throughout the home.

Seaton said anyone with the same type of construction should have all of their pipes pressure tested.

“This is the first time in my career I have ever seen anything like this,” he said.