One man is dead after two transport trucks collided on Highway 401 in Milton on Tuesday night.

It happened in the westbound lanes of the highway near Trafalgar Road shortly after 11:30 p.m.

"Two transport trucks (were) involved in a rear-end collision and what we believe right now is that transport trucks were actually in queue, lined up going through a construction zone just a little further west of here. Traffic was going maybe 15-kilometres an hour or stopped… and the last transport truck came in and slammed into the back of the rear truck," OPP Sgt. Kerry Schmidt told CP24 at the scene. 

A third vehicle, a minivan, sustained minor damage after being struck by debris from the crash.

The driver who struck the back end of the slowed tractor-trailer has been identified by police as a 61-year-old man from Ajax. He was pronounced dead at the scene. 

The driver of the other truck that was rear-ended was taken to hospital with minor injuries.

"(They were) two loaded transport trucks, an absolutely devastating crash," Schmidt said early Wednesday morning.

"The cleanup was pretty complicated but we got out of here pretty quickly. We are just in the process now of cleaning up the last bit of debris and sand from all the absorbent material and the diesel that spilled on to the ground... It has been about a six-seven hour cleanup here." 

Westbound lanes of the highway were closed for several hours Wednesday morning but the highway has since reopened.