A propane explosion that leveled a building in Maine narrowly missed a school bus that had just picked up kids. One firefighter was killed and at least seven other people were hurt. The building had just been built.

Cellphone footage taken right after the explosion in Farmington, Maine, shows debris falling like snow. Franklin County Sheriff Scott Nichols was one of the first on the scene.

"You know, I spent a year in Iraq. It's the closest I can explain it. It was just total devastation," Nichols said.

From the air, the extent of the blast zone is visible. The entire building that housed an organization for people with disabilities was flattened by the suspected gas explosion. It was evacuated at around 8 a.m. when a worker smelled gas. The blast occurred moments later.

Firefighters looks through debris at the scene of an explosion Monday, Sept. 16, 2019, in Farmington, Maine. AP

Lisa Marston had just been urged to leave by a maintenance man.

"I just kind of went around behind the shed and just tucked because things were just flying everywhere," Marston said.

Monday afternoon, the town held a procession for Captain Michael Bell, the firefighter who was killed. But the toll could have been much worse.

The blast was heard and felt for miles. Fortunately at the time of the explosion, the building was not yet in full use. Multiple homes in the area were also damaged.

The state and Bureau of Alcohol, Tobacco, Firearms and Explosives investigations will begin Tuesday, but so far it's believed to have been an accident.