Route 309 in Lynn Township was closed for nearly four hours Tuesday due to a serious crash at the base of the Blue Mountain.

The crash occurred just before noon involving a tractor trailer and a second vehicle almost unidentifiable.

Route 309 was closed at the intersection with Mountain Road in Lynn Township and Route 895 in West Penn township by the Pennsylvania Department of Transportation utilizing heavy trucks to block the roadway. The accident occurred during a moderate rain storm and heavy fog. State police at Fogelsville are investigating the incident.