A semi-truck crash shuts down a crucial border route; a tanker wreck causes chaos in Toronto.

Rookie Sonny faces a 40-car pile-up that turns a major highway into a war zone.

A courier truck rolls over; a vicious storm puts Mark in the middle of a crash zone.

A semi smashed into a building; a tractor-trailer crashed in deep mud.

Gary's team fights to upright a battered trailer; a rookie's first shot as lead rotator operator.

Kyle tangles with a wreck that will prove if he can lead the team; Sonny heads to a jackknife scene.