Toronto police are investigating a collision that left a passenger's arm severed after the vehicle he was in crashed into a brick wall on Lake Shore Boulevard Thursday morning.

The crash occurred at about 2:08 a.m. when police responded to a call that a white Honday Accord travelling eastbound with two occupants had been sheered in half.

The passenger, a 36-year old man, was taken to hospital. Investigators said his right arm was severed below the shoulder after the crash.

The driver, a 30-year-old man, was also taken to hospital. Police said he suffered serious injuries.

Parts of Lake Shore Boulevard were shut down for seven hours on Thursday as police investigated the scene.

The cause of the crash is still unknown but police said drugs and alcohol weren't involved in the collision.

Investigators still haven't determined how fast the car was going when it lost control

According to CTV's John Musselman, the vehicle was heading eastbound on Lake Shore Boulevard near Royal York when the car veered off the road and hit a fire hydrant. The car then careened forward, smashing into a pole before crashing into a brick wall.

A homeowner whose property includes the brick wall told CTV Toronto the noise of the crash jolted him out of bed.

Mike, who did not want to reveal his last name, said he's lived on the street for 30 years. He said speeding along the Lake Shore is a problem, especially late at night.

"A policeman stays there a lot of mornings and he gets a lot of people. He pulls them over but they go too fast in this area," Mike said.

Sgt. Larry Zimmerman told CTV Toronto that because of how early the collision happened, witnesses so far have been able to tell police little more than they "heard a loud noise."

"We're in the process to see if there are any cameras around and videos," Zimmerman said.

With a report from CTV's John Musselman.