Montreal police arrested a 35-year-old man Monday morning following a car theft and crash that took place in the downtown core.

Around 5:15 a.m. a man forced his way into a car that was stopped at a red light at the corner of St. Urbain St. and Ontario St.

After pushing the car's owner away, the man sped south, with witnesses saying he reached 100 km/h before he smashed into the side of Complexe Desjardins, just one block to the south.

Witnesses who saw the crash, not realizing the car was stolen, rushed to the man's rescue and pulled him out of the vehicle.

That's when the man tried to steal another car.

"He tried to open my passenger side gate and entered from it and tried to reach the driver's seat and other people, like, grab him out and like put him on the ground," said Mitul Jain.

The witnesses then pinned the car thief suspect to the ground until police arrived a few minutes later.

Jain and other witnesses said the man, who was bleeding from the car crash, appeared to be intoxicated.

Meanwhile paramedics treated the 31-year-old man who was assaulted and thrown to the ground.

Const. Veronique Dubuc said the victim was not badly hurt.

"He's shaken up. He was surprised at this hour, well at any hour I would be surprised, but he was surprised by the event," she said.

The suspect is facing charges of dangerous driving, impaired driving, and robbery.

With files from Julian McKenzie