COATESVILLE, Pa. — Seven school buses were severely damaged in an overnight fire just outside an eastern Pennsylvania town plagued by arsons.

Authorities in West Brandywine Township, Chester County, said firefighters were called to North Brandywine Middle School around 3 a.m. Sunday.

Investigators determined the fires had been deliberately set. No suspects have been named.

Damage is estimated at $400,000.

Investigators say there have been 66 arsons since January 2008.