All lanes on Highway 400 have finally reopened after a 10-tonne military vehicle that was towing a similar car flipped over, causing traffic chaos during Wednesdays' evening rush hour.

The crash happened on the southbound lanes of Highway 400 between Highway 89 and Innisfil Beach Road. That section remainedclosed while police investigated but officials say all lanes will be reopened by 7:30 p.m.

Ontario Provincial Police Const. Dave Woodford said the vehicle was carrying a trailer hauling a second 10-tonne military car. The truck came off the trailer, causing both vehicles to rollover.

The driver was not injured in the crash.