A 15-year-old boy was arrested Wednesday in connection with a fire in a Port Orchard middle school, according to the Kitsap County Sheriff’s Department.

The boy was booked into a county juvenile detention facility on investigation of first-degree arson and second-degree burglary, the sheriff’s department said in a Facebook post.

Sheriff deputies responded to Marcus Whitman Middle School Wednesday morning after an alarm went off. When officials arrived, they found part of the school on fire. Sheriff’s spokesman Scott Wilson said he wasn’t sure where in the school the fire started.

The flames caused “substantial damage” inside the school, the post said.

No one else was inside at the time and no injuries were reported, Wilson said.

The South Kitsap School District declined to comment.