Casper, WY – An explosion that leveled a Casper home was an isolated incident caused by a leak from a broken natural gas connection inside the house, according to a fire investigator who examined the early September explosion.

The investigation did not ultimately determine what sparked the natural gas that had filled the south Casper home and caused the blast. However, Casper Fire-EMS Investigator Jason Parks said by phone Monday that a number of potential ignition sources were found in the house’s basement, including a decades-old furnace with a permanently burning pilot light.

The home, which had stood at the end of a cul-de-sac overlooking the intersection of Arroyo Drive and West 38th Street, was entirely destroyed. Nobody was in the home at the time and no one was injured or killed in connection with the explosion.

Windows throughout the area rattled as a result of the blast and the explosion could be felt at least a mile away. Police closed portions of the residential neighborhood for the afternoon. Wood, nails and pink insulation littered the area below the Plateau Place cul-de-sac. Although flaming debris set neighbors’ yards ablaze and damaged fences, it did not ignite any other structures.

On Monday, in response to a Star-Tribune request for information made under Wyoming public records law, Casper Fire-EMS released Parks’ report, which states that an examination of the natural gas connection between the meter and the home showed no leaks.

However, just inside the house’s foundation, investigators found damage to a pipe fitting inside a basement utility room and designed to carry gas to a furnace and a hot water heater. Parks said by phone Monday that the examination indicated the pipe fitting was damaged by pressure put on it as the home’s hillside foundation settled. Natural gas then leaked from the pipe before a spark ignited the blast.

The home had been unattended for days: a caretaker spent the holiday weekend out of town. The homeowner largely lives out of state and had not been on the property for months, the report states the men told police and ATF interviewers. Responses to public records requests do not indicate that authorities ever considered the investigation criminal.

In the days following the blast, at least five homes — in addition to the house leveled by the explosion — were ruled uninhabitable by city building inspectors, according to a police spokeswoman. At least a dozen displaced neighbors stayed with friends and family, Rebekah Ladd, the spokeswoman, said in September.

On Monday, Ladd said that she did not know how many of those people had returned to their homes and referred the Star-Tribune to the city building and inspections department. Officials overseeing that agency did not immediately respond to late Monday afternoon phone messages requesting information for this story.

Neighbors on Monday evening, though, said that four of the five homes have remained unoccupied and are awaiting repairs. Some of those homes had windows with plywood covering that could be seen from the street.

The Wyoming State Fire Marshal’s Office and the Bureau of Alcohol, Tobacco, Firearms and Explosives also contributed to the investigation. Casper police have said the federal agency was assigned the investigation out of an abundance of caution and investigators quickly ruled out the possibility of an explosive device or clandestine drug lab causing the blast.

Black Hills Energy, which supplied natural gas to the home, participated with the fire department investigation, a company spokesman said. Michael Howe said Monday afternoon that the company agreed with the agency’s finding that company’s infrastructure was not a cause of the blast.