A woman is dead and another man is in serious condition in hospital after a collision in the eastbound lanes of the Gardiner Expressway early on Sunday morning.

Toronto police say a white 2015 Audi R8 travelling at a high rate of speed rear-ended a grey Nissan just east of Islington Avenue, sending the Nissan straight into a guardrail.

The vehicle then flipped over onto its roof.

A 58-year-old woman who was in the Nissan was pronounced dead in the hospital, police say.

The driver of the Nissan, a 61-year-old man, was seriously injured and taken to a hospital trauma centre for treatment.

Police say the driver of the Audi R8 fled the scene on foot.

The eastbound express lanes of the Gardiner were closed for several hours to allow a collision reconstruction team to complete their on-site investigation.

“There were a number of motorists that stopped to render assistance. Some were observed taking video of the scene moments after the collision. Police are appealing to those witnesses, and any others that may have information that would assist in the investigation, to contact police.”

Investigators are also asking anyone who may have seen the Audi R8 before the collision to come forward and talk to them.

Anyone with information, including CCTV or dash camera footage, is urged to contact police at 416-808-1900 or Crime Stoppers anonymously at 416-222-TIPS (8477).