Highway 400 re-opened Sunday morning after a massive multi-vehicle collision closed lanes in both directions.
Two drivers involved in the crash, a 26-year-old man and a 22-year-old woman, have been charged with dangerous driving and criminal negligence.
Police say a Volkswagen Golf and a Honda Civic may have been racing in the southbound lanes just northwest of Newmarket when the Civic lost control and began to roll, striking the Golf.
Two other vehicles travelling behind them swerved to avoid the crash, but both vehicles hit the guardrail and ended up in the northbound lanes of Highway 400.
Eleven people were taken to Southlake Hospital.
Two had serious injuries and nine had minor injuries, including a 4-year-old child.
Police say all passengers were wearing seatbelts.
With a report from CTV's Tom Hayes and files from The Canadian Press.
