Seven school buses were set on fire at North Brandywine Middle School, just two miles north of Coatesville.
Firefighters were called to the school in Chester County at approximately 3 a.m. Sunday.
Investigators say the fires were deliberately set and that damages from the fire total at least $400,000.
West Brandywine Township is just north of Coatesville, a town that investigators say has had 66 arsons since January 2008, the Associated Press reported.
Two suspects have been arrested in at least 10 of those fires, but dozens remain unsolved.
To learn more about the suspects who were arrested, click here.
