Investigators comb through the debris Tuesday as they try to find clues why a building exploded Monday in Farmington. The blast killed Farmington Fire Capt. Michael Bell and injured seven others. Credit: Gabor Degre | BDN

A propane line that had leaked 400 gallons of propane from a tank over the course of a weekend was responsible for the explosion that leveled the LEAP Inc. building in Farmington last week, killing a firefighter and injuring seven others.

The state fire marshal’s office Friday confirmed that the propane leak was responsible for the explosion, following an investigation by state and federal officials who interviewed more than 100 people about the blast.

The propane tank at the LEAP building had been filled Friday, Sept. 13 with 400 gallons of propane but was empty when the building exploded just after 8 a.m. last Monday, Sept. 16. The explosion seriously injured six Farmington firefighters and killed Fire Capt. Michael Bell. A LEAP employee, maintenance supervisor Larry Lord, was also severely injured in the incident.

Investigators located the leak in a propane line buried under LEAP’s paved parking lot, said Stephen McCausland, a spokesman for the Maine Department of Public Safety. The line connected an outdoor propane tank at the back of the property to the basement of the building. The leak was “significant,” McCausland said, and its cause — as well as what sparked the explosion — is still unknown.

Credit: J.P. Fortier | AP

McCausland said the distinct smell of propane may have been diluted by the soil under the parking lot where the leak occurred. He said investigators believe the propane permeated the soil under the parking lot in addition to leaking into the basement.

The explosion leveled the two-story building that had been renovated last year.

Lord and another LEAP employee checked the tank early Monday before ushering people out of the building minutes before it exploded. Lord was in the basement, along with firefighters “TD” Hardy and Joseph Hastings and Capt. Scott Baxter when the explosion happened. Upstairs, Capt. Bell was on the first floor with his brother, Fire Chief Terry Bell, who was standing near the rear door of the building, McCausland said. Deputy Fire Chief Clyde Ross and firefighter Ted Baxter, Scott Baxter’s father, were in the parking lot.

Credit: Courtesy of Courtney Webster

As of Tuesday, the elder Baxter, Hardy and Ross had been released from Maine Medical Center in Portland. Scott Baxter was in serious condition and Bell was in fair condition, according to Maine Medical Center. Lord was still in critical condition at Massachusetts General Hospital in Boston.

The explosion could be heard from Livermore, more than 30 miles away. It destroyed two out of 11 manufactured homes in a nearby park and caused the rest to be uninhabitable. Houses surrounding the building also sustained damage such as broken windows, and insulation from the building could be seen in Farmington’s downtown, nearly a mile away.

LEAP has since relocated to donated office space in Wilton.