A firefighter killed in the fierce propane explosion in Maine on Monday was the brother of the town's fire chief who himself was injured in the blast, officials revealed.

The explosion shattered the two-story building that housed LEAP Inc., a nonprofit that serves people with cognitive and intellectual disabilities, just a couple of months after it was finished.

The blast, which erupted after fire crews arrived to investigate the smell of gas killed 68-year-old Fire Capt. Michael Bell and injured his brother, Fire Chief Terry Bell; five other firefighters; a maintenance worker for LEAP; and an ambulance worker, officials said.

“It’s a war zone. It’s just a mess,” said Scott Landry, a member of the Farmington Town Select Board. “The building is gone.”

The blast was so powerful it blew a vehicle across an intersection and damaged nearby buildings. Paper, insulation and building debris rained on the area.

Four of the firefighters were in the intensive care unit at Maine Medical Center in Portland, while the maintenance worker was being treated at a hospital in Boston, officials said. One firefighter and the ambulance worker were treated and released.

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The blast hit around 8:30 a.m. in this town in western Maine, about 70 miles north of Portland.

Neighbors heard a thunderous boom that rattled homes and knocked pictures off walls. Flying paper and dust made it look as if a snowstorm had hit.

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Gov. Janet Mills — who is from Farmington and whose office said she knew the firefighter who died — ordered flags lowered to half-staff across the state. Mills also visited the scene and promised the state fire marshal’s office will investigate.

“We’re going to get to the bottom of as much as we possibly can to protect this community, to protect all other communities and make sure this doesn’t happen again,” she told reporters.

The Associated Press contributed to this report.