Fire investigators said spontaneous combustion triggered a fire that damaged the Hawaiian Mission Elementary and Intermediate School in Makiki on Sunday morning.

Fire spokesman Capt. Kenison Tejada said pockets of decomposing wood material — similar to sawdust — in the attic generated enough heat to ignite.

The fire began in the school's attic and caused about $60,000 in damage, he said.

The fire sent thick black smoke out of the school's auditorium and main office building. No one was injured and summer classes continued at the campus yesterday.

Deloris Trujillo, superintendent of schools for the Seventh-day Adventist Church, which runs Hawaiian Mission, said the school's insurer is sending a structural engineer to assess damage in the building that served as an auditorium, cafeteria, music room and main office building.

"We don't know exactly how much damage has been done," she said. "I think it's going to go above the (estimated) $60,000 mark, though."

No classes are being held in the damaged building and offices have been moved elsewhere on campus, she said.

Staff writer Loren Moreno contributed to this report.

Reach Curtis Lum at culum@honoluluadvertiser.com.