Editor's note: This article has been updated with information from Chelsea Police Chief Ed Toth.

A fire that appeared to have been deliberately set caused a brief evacuation of Chelsea High School Thursday morning.

Chelsea High School Principal Mike Kapolka grabbed a fire extinguisher and put the blaze out before it could spread beyond the bathroom, Superintendent Andrew Ingall said.

Chelsea Police Chief Ed Toth said the fire was arson. The Chelsea Area Fire Department is investigating. Toth said he is committed to finding out who started the fire.

Ingall declined to comment on whether a student was to blame for the fire and whether anyone had been suspended.

A student passing by a boys’ bathroom noticed smoke about 9:45 a.m. and reported it to the nearest adult, who was in the media center, Ingall said. From there, it was reported to the office and the fire alarm was activated.

Students were able to return to the building after about 10 minutes, Ingall said. Officials used industrial-sized fans to clear smoke out of the building.

“Fortunately, it was a nice day and we were able to open lots of windows,” he said.

Ingall praised Kapolka and the student who reported the fire for their actions. “Thanks to Mike’s quick action this is really a minimal incident,” he said.

The bathroom is expected to remain closed for the rest of the day, Ingall said. All other areas of the school are functioning normally.