Police are saying a serious crash Wednesday afternoon between a car and motorycycle may have happened because of two motorcycles street racing.

It happened at McKercher Drive and Degeer Street on the city's east side. It prompted police to close off traffic in the area while they investigated.

The 21-year-old motorcyclist was rushed to hospital with serious injuries. They are described as life threatening.

Witnesses on scene said they saw a motorcycle try to slam on its brakes, but ended up crashing into the side of the car.

The driver of the car was not injured.

Police also arrested another man who was stopped in connection with the crash. Witnesses told a CBC News reporter at the scene that officers were questioning the man about street racing.

This morning, police confirmed that the 20-year-old driver of the second bike was taken into custody but has not been charged.

The accident is still under investigation.