All northbound lanes of Highway 400 have reopened after a military vehicle lost control of a weapon it was towing in Innisfil.

A convoy of military vehicles were travelling along the highway just before noon on Thursday, when one of the vehicles lost a trailer carrying an artillery cannon. As a result, the cannon flipped over near Simcoe Road 89.

OPP closed the highway for several hours, while crews worked on up-righting the cannon. It has since reopened.

It’s unclear what caused the cannon to flip.