A four alarm fire accidentally sparked by dental equipment tore through a Babson Street building in Mattapan late Monday afternoon, injuring two residents, fire officials said.

Boston firefighters responded around 4:05 p.m. to 130 Babson St., next to the Mattapan Campus of Pope John Paul II Catholic Academy. The 2 1/2-story wood-frame residence, which also houses a dentist’s office, was burning heavily by the time firefighters arrived, according to the Boston Fire Department.

Two residents were pulled from the burning building. The Boston Fire Department reports an elderly man -- the dentist -- told firefighters at the scene that his son was still inside the house. Emergency Medical Technicians treated both victims at the scene, and the son was taken to the hospital in serious condition, fire officials said.

Boston Police detectives responded to the scene due to the severity of the unidentified victim’s injuries. A firefighter also suffered a non life threatening injury.

It took firefighters about an hour and a half to knock down the fire, working from the exterior of the building and ordered off the roof as the fire ripped through it. Firefighters were later permitted back into the building to extinguish hot spots.

The four-alarm fire caused an estimated $500,000 of damage, the fire department reports. Fire investigators determined the cause to be accidental, originating from a piece of dental equipment being used.