No suspects have been identified, said city Assistant Fire Marshall William Glover Jr.
The fire began in four different places at the old Arlington School on North Webb Street in West Gastonia. It took about an hour for 40 firefighters to control the fire, and one firefighter was treated for minor burns, Glover said.
Authorities said they don't know how anyone broke into the school because when firefighters arrived, all the doors were locked, he said.
School officials had stored office equipment and other items inside the building. Several curtains and couches were set on fire, and the building looked as if somebody had ransacked it, Glover said.
"There were a lot of mischievous things," he said, "just tearing stuff up, pulling drawers out, stuff like that."
The building in the past year has been the target of several break-ins, he added.
Arlington School, built in 1924, closed after the 2003-04 school year because the building was in such disrepair.
A new school, Sadler Elementary, opened after county commissioners pledged money and voters approved a school bond package to finance the nearly $10 million project.
Authorities are asking people to call Crime Stoppers at (704) 861-8000 if they have any information about the case.
