An overheated kiln in an art room at Lincoln Elementary School set off a fire sprinkler in the classroom just as students lined up for dismissal, the School District of Palm Beach County said.

All students and staff were evacuated safely out of the building, while Riviera Beach Fire Rescue responded and gave the all clear, the district said in a message to parents.

The evacuation delayed dismissal by up to 20 minutes and some some classrooms sustained water damage, this district said.

As a result, the school’s open house that was scheduled for Wednesday evening has been postponed.