Crews are working to clean up a stretch of Highway 400, north of Vaughan, after thousands of litres of human waste spilled from a tractor trailer.

It happened at around 9:10 a.m. in the southbound lanes of the highway near King Road.

Ontario Provincial Police said a tractor trailer hauling 42,000 litres of filtered “human sludge” sprang a leak, likely because of a faulty valve.

Some 25,000 litres of the waste spilled before the leak was fixed.

Most of the waste is believed to have spilled over onto the shoulder rather than on the roadway and the highway remains open. One right lane is blocked for cleanup.

However crews from the ministries of transportation and the environment have been dispatched to clean up the waste.

Police said there could be a visual distraction because of the cleanup.