Two workers were flown to Boston hospitals after they were badly hurt during an explosion and fire at Student Transportation of America's facility in Bradford, New Hampshire.

According to the state fire marshal's office, the incident happened about 10:35 a.m. on Thursday as workers performed maintenance on a propane-powered school bus.

"When the first crews arrived, they witnessed heavy fire and smoke pouribng from the building before locating two people trapped inside," Fire Marshal Sean P. Toomey stated in a news release. "Crews worked to free the individuals, who suffered significant burns." 

Bradford Fire/Rescue Department sought help from other fire departments in the region to battle the 5-alarm blaze, Toomey said. Firefighters were challenged initially by a lack of a nearby water supply and staffing due to the size of the fire.

In a statement to School Bus Fleet, STA spokesperson Jen Holzapfel confirmed the fire occurred and that the conmpany is fully cooperating with local fire and police investigators.

"We were saddened to learn that two employees were inside at the time of the incident," Holzapfel said. "Our thoughts are with these employees and their families. We wish them a swift and full recovery."

She expressed gratitude on behalf of STA for emergency crews and first responders.

"We plan to assess the damage to the warehouse and buses as soon as possible and will work closely with the district should there be any impact to student transportation services in the coming weeks," she said.