PINE TWP, Mercer County — An overheated coffee maker is blamed for starting a fire this morning that destroyed the kitchen of the student union building at the George Junior Republic private reform school, authorities said.

“The coffee pot was left unattended and melted into the (wood) counter,” said state police deputy fire marshal Trooper Brian Crouch, who ruled the electrical fire accidental.

The fire was discovered shortly before 10 a.m. No one was inside the 100-by-80-foot building when the fire started, authorities said.

Christopher Holmes, chief of the Pine Township Engine Company, estimated damage at $15,000 to $25,000.

“They’re going to have to redo the whole kitchen,” he said.

The building includes a movie theater and is generally used during the evening for activities for the troubled youths, some 500 boys between 8 and 18 years old.

“It’s pretty much vacant during the day,” Holmes said of the building.

An employee found the fire when he went for supplies. Crouch said the building was last occupied about 8:30 p.m. Sunday.

More than two dozen firefighters from several departments were called and forced the door open to get inside, authorities said.