Eastside Fire and Rescue and Issaquah Police are considering as suspicious a fire on the grounds of Grand Ridge Elementary School in the Issaquah Highlands on Tuesday night.

According to Fire Marshall Bud Backer, crews were called at 10:25 p.m., and arrived at the scene at 10:31 p.m., where they found a portable toilet structure on fire.

Backer said it was fortunate the fire did not catch on to any of the nearby buildings.

“It looked as though it had been burning for a while by the time we got there. There wasn’t much left of it.” he said. “Being next to a portable [classroom], it could have easily spread to that building.”

Backer said there would be an investigation into the cause of the fire.