A tractor trailer hauling ash from the waste-to-energy plant in Biddeford overturned early this morning on Haigis Parkway in Scarborough.

The cause of the single-vehicle accident, which occurred shortly before 1 a.m., remains unclear. Haigis Parkway was closed between Payne Road and Route 1 until 10:15 a.m.

Multiple wrecker services were called in to help right the tractor trailer. Authorities also notified the Department of Environmental Protection.