The OPP have closed the two left lanes of the westbound, and the left lane of the eastbound 401 between Guelph Line in Milton and Highway 6 near Morriston.
The closure comes after a tractor trailer jumped the guard rail and jack-knifed onto the median. There was a fuel spill as a result.
OPP say the lanes will be closed until about 2 this afternoon. News Now will have updates on the situation, as work crews clear the scene.
