The cause of a fast-moving fire that sent students scrambling to safety at a yeshiva Thursday is under investigation.

Charred debris remains at the site of the yeshiva dormitory on East Funston Avenue in Spring Valley. More than 80 firefighters battled flames at Bais Medrash of Rockland.

"There was a heavy volume of fire on two floors and the attic area," said Bob Johnson, the chief of the Spring Valley Fire Department. "There are teenage children who are here all the time, so it could have been a lot worse."

The fire started before noon and quickly engulfed the dorm. Every student managed to flee the fire before firefighters arrived, authorities said.

Firefighters from five fire departments worked to get the blaze under control. By 1:30 p.m., the fire was out and the structure was likely a complete loss because of the damage.

One firefighter was treated for minor injuries.