Core eastbound lanes of Highway 401 remained closed east of Kipling Avenue early Saturday afternoon after a multi-vehicle collision.
The highway's four centre lanes were closed between Dixon Road to Highway 409 after an accident involving an 18-wheeler and three cars.
Traffic was diverted into the collector lanes, and bottlenecked. Some drivers were delayed for over an hour.
Emergency crews had to pull people out of vehicles and transport them to hospital. One person was seriously hurt and six others sustained minor injuries.
The cause of the crash is unknown, but one truck driver blamed summer construction for the increase in accidents.
"People live busy lives, and you're creating a backlog with it, and then they're trying to get around it and taking that little extra chance," said Bart Mobbs, a tow truck operator.
"When that happens, that's when the accidents occur."
Police said the accident, involving a truck and two cars, happened shortly after 7 a.m. The lanes re-opened after 2 p.m.
With a report from CTV's Jim Junkin
