A section of the highway was closed after a tractor-trailer drove into a parked truck that was part of a crew involved in cleaning up the mess after an earlier collision.
The accident involving the tractor-trailer happened at Winston Churchill Boulevard, just after midnight.
After hitting the truck the tractor-trailer spun out of control, crossed all lanes of traffic and lost a full tank of diesel fuel, according to the OPP.
One worker was injured in the accident. The driver of the tractor-trailer was also taken to hospital.
Police initially said they expected to reopen the highway after a few hours, but later changed that assessment and said the eastbound lane could be closed all day.
The damage from the fuel spill was a lot worse than first thought, they said, and the roadway may need to be resurfaced.
The driver of the tractor-trailer has been charged with careless driving.
In Vaughan, north of Toronto, a motorcyclist was killed overnight when his bike was hit by a truck coming from the opposite direction at the intersection of Major Mackenzie Drive and Jane Street.
The truck driver was not hurt.
No names or ages have yet been released.