A three-vehicle crash closed westbound lanes of the 401 west of Woodstock early Thursday morning.
Oxford County OPP say a tractor-trailer and two other vehicles were involved in a crash around 4 a.m.
The collision occurred in the westbound lanes a couple of kilometres before the ONroute gas stations on the highway.
Traffic was diverted from the 401 at Norwich Avenue and Mill Street, but backed up quickly as dawn approached.
The transport truck ended up on its side, with 450 litres of diesel fuel spilling.
Three people were transported to hospital, two with minor injuries, the other with serious but non-life threatening injuries.
The highway started to reopen around 1:30 p.m.
