HARRISON - Officials say training may have saved the lives of five firefighters who are now recovering from injuries sustained while battling a five-alarm fire Sunday in a Harrison building.

News 12 New Jersey obtained a cell phone video of a dangerous explosion that happened during the fire.

The video shows the firefighters standing next to the burning building when a backdraft caused a huge explosion that sent the firefighters hurtling down the street. A backdraft is an explosion that occurs when an oxygen-deprived fire suddenly gets the air that it needs.

Firefighters train diligently to know how to protect themselves from such an incident. They know to look for signs like dark brown smoke, and to crack a window open on the opposite side of where the fire is in a building.

The Harrison fire chief says newly constructed homes may carry the greatest potential for backdrafts due to their insulation.

One firefighter who was injured remains hospitalized today.