BELLEFONTE, Pa. -- Nearly 48 hours after a massive fire tore through the third floor of the Old Cadillac Building in Bellefonte, a state police fire marshal has ruled the fire as accidental.

In a release from State Police at Rockview, the fire marshal said that a woman and her teenage son left Christmas tree lights plugged in.

The woman reportedly woke up to a smoke-filled apartment and her Christmas tree engulfed in flames.

Twenty-four people are staying in a hotel or with family for the holidays, after the fast-moving fire damaged all of the apartments on the third floor.

Apartments on the second floor, as well as the Bellefonte Senior Center and the officer of Representative Kerry Benninghoff, suffered extensive water damage.

Bellefonte firefighter Tim Knisely told WJAC-TV Thursday that if first responders hadn’t jumped into action so quickly, lives may have been lost.

As co-chair of the Pennsylvania Fire Sprinkler Coalition, Knisely said that the fire and damage could have been contained if fire sprinklers were installed in the 95-year-old building.

“The fire started in an occupied space of the apartment,” said Knisely.

“If the sprinkler system was properly designed and installed and maintained, I’m confident that one sprinkler head, or two, would contain the fire, allowing everyone to escape safely.”

Starting Jan. 1, all new townhomes constructed in Pennsylvania must have a sprinkler system installed.

By 2011, every new home built in the state must have a residential sprinkler system installed to meet code.

Knisely has been battling building associations for months, saying that fire sprinkler installation costs less than $2 per square foot and that they are activated independently.