Two westbound lanes of the Highway 401 near London have been reopened after a tractor trailer caught on fire.

Middlesex County OPP officers say it happened at about 7:04 a.m. Monday in the westbound lanes at Westchester Bourne.

Police believe a mechanical failure on the trailer section was the cause of the fire.

Police reduced the westbound 401 to one lane as emergency crews investigated. Crews had to extinguish the fire in the trailer portion of the vehicle and remove it from the roadway.

Traffic was backed up in the area after the fire.