BUZZARDS BAY — A fuel tank fell off a tractor trailer and ruptured on Route 25 Wednesday afternoon, spilling between 50 and 100 gallons of diesel fuel, according to state police and the Massachusetts Department of Environmental Protection.

Part of the westbound highway was closed after the fuel spill, which started near the Bourne Bridge, was discovered shortly before 2 p.m., state police said.

The tank came from a J. Polep Distribution Services truck from Providence, said Edmund Coletta, a DEP spokesman. The saddle tank fell off the truck and spilled fuel from the bridge to just prior to Exit 3 on Route 25, police said.

The right travel lane was closed during clean-up efforts, which were being done by Frank Corp. Environmental Services, and most of the effects were to the breakdown lane and soil off the road, Coletta said.