Monday was an unscheduled day off for students at Tweedsmuir Public School in London.
The Thames Valley District School Board says it had to close the school for the day because of an act of vandalism.
London police say there was a break-in at the school and gasoline was poured inside a classroom. A small fire was reported and damage is estimated at $5,000.
The Board says the school will re-open on Tuesday.
Anyone with any information that could lead to a suspect is asked to call London police or Crime Stoppers.