Around 7:25 a.m., the driver of a Toyota RAV4 travelling eastbound lost control of his vehicle and hit a cement barrier. Unable to swerve out of the way, a tractor trailer collided with the SUV, said Sgt. Dave Woodford of the Ontario Provincial Police.
The crash sent the Toyota's three occupants to hospital. The male driver suffered minor injuries, while the two female passengers were airlifted to St. Michael's Hospital. One woman is critical condition, while the other sustained "life-threatening injuries," Woodford said.
Woodford said he expects the eastbound lanes of the 401 to re-open around 11:30 a.m.
Sunday's collision comes after the first big storm of season heaped snow on southern Ontario, causing headaches for motorists across the region.