Fire officials said a copper thief might have knocked over a water heater in a vacant house on Campbell Street, breaking a gas line and leading to a buildup of gas that caused the house to explode early Monday.
Fire, gas and Public Service Commission officials were at the scene Monday afternoon. Fire investigators were searching for the ignition source that sparked the explosion.
No electricity was on in the house at the time, fire department Maj. Ed Davis said.
The thief or thieves apparently cut off the pipe and valve that feeds water into the top of the water heater over the weekend. Then they tipped over the water heater.
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"When they did that, it looks like it tore out the flex hose" that feeds gas to the water heater's heating elements, Davis said.
No one was thought to be injured when the house at 457 Campbell Street, near Transylvania University, exploded before 1 a.m., sending wood, drywall and debris flying.
Davis said the airborne gas burned away in an instant, and there was only a small fire when firefighters arrived.
Nearby houses might have been damaged by the heat and debris, but Davis said he thought any damage would have been minor.
The house was vacant, he said. Neighbors told fire officials a squatter had been staying there.
Davis said investigators searching the rubble Monday afternoon had not found signs that anyone was inside.
"We have a lot of questions and not a lot of answers right now," said Columbia Gas spokeswoman Lisa Smith. "We're grateful there were no injuries."
The gas, which was shut off in June, was turned back on Dec. 12, she said. But the company didn't relight any gas appliances because there was no electric or water service at the house. The company did test the lines, and there were no leaks.
On Friday, a meter reader stopped at the house and found no gas had been consumed since Dec. 12.
However, there was some gas used since Friday — an amount about equal to what would be consumed in a month during the summer at a home, Smith said.
"That's a lot since Friday," she said.
Company workers tested for leaks Monday morning near the house and on the street; there were none.