Matchbooks and paper wedged in the exterior walls of Pleasant Green Elementary School have fire officials confident that a fire there Saturday was the result of arson.

Investigators found remnants of matchbooks and pieces of burned newspaper stuck in cracks in three places around the school. Two of the fires burned themselves out, but the third ignited plywood and other lumber under the building's aluminum skin and then burned through the roof before being spotted several hours later, Salt Lake County Fire Battalion Chief David Limberg said.Two youths were seen on top of the school building, at 8201 W. 2700 South, but no suspects have been identified in the arson so far, Limberg said.

The fire damaged a portable building on the south side of the school that is connected to the main building by a hallway. Smoke damage in other parts of the building may drive up the $15,000 damage estimate.