STAFFORD TOWNSHIP, N.J. (CBSNewYork/AP) — Investigators say natural gas leaking from an underground main traveled into a New Jersey house, built up in its basement and exploded when it came in contact with an open flame from an appliance in the house. The blast injured 15 people.

The Ocean County prosecutor’s office says the most likely source of Tuesday’s explosion in Stafford Township was a pilot light from a hot water heater or furnace, or a spark from a thermostat.

Two gas company workers remain hospitalized in critical condition.

Investigators say gas leaked from the main in the street in front of the house, traveled along a water pipe into the unoccupied house’s basement, and exploded when the flame or spark touched it.

Utility workers were restoring service to the neighborhood Wednesday. New Jersey Natural Gas employees were going door to door to about 300 homes in the Oak Avenue and Cedar Run section of Stafford Township, where residents spent Tuesday night into Wednesday morning without heat with temperatures in the teens.

Gas crews and emergency responders were investigating a strong smell of natural gas Tuesday when the home, which was undergoing renovations, exploded.

A police car’s dashboard camera recorded a fireball followed by a downpour of debris.

“It happened so quickly,” said fire Chief Jack Johnson, one of the first responders who was trying to locate the source of the leak when the explosion happened. “With the explosion, we had debris all around us just come from nowhere.”

Video from the scene showed smoke billowing from the explosion site and piles of debris in the road next to where the house once stood.

“It looks like a war area,” said Max Von Ness, a plowing contractor who was nearby when the explosion occurred. “It’s just destruction. There’s debris all over the place.”

Seven gas company workers were injured, including the two who were critically hurt, along with six firefighters and two emergency medical service technicians who sustained concussion-like injuries.

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