Highway 401 westbound was shut down for about 12 hours Thursday after a crash involving two tractor trailers killed one person.

The collision occurred around 12:30 a.m. when the three trucks travelling westbound collided east of Union Road.

A white Volvo tractor trailer travelling eastbound crossed the centre median, rolled over, and collided with a westbound white Freightliner truck.

Police say one person in the Freightliner was killed in the crash.

He has been identified as Gary Lent, 66, from Etobicoke.

The male driver and lone occupan of the Volvo was transported by ambulance with serious injuries to hospital, where he is currently listed in good condition.

No word from police if charges will be laid.

Shortly after 12 p.m. Thursday, one lane of the 401 was re-opened to traffic. The entire highway was open to traffic around 5:30 p.m. Thursday.

The OPP Technical Traffic Collision Investigators (TTCI) are attending the scene to assist with the investigation.