About 200 cyclists, some riding with children, shut down the westbound lanes of the Gardiner Expressway last night in what police called a dangerous stunt.

The Gardiner was shut down for almost half an hour when the cyclists, most of whom were wearing helmets, stormed onto the westbound lanes from Lower Jarvis St. around 7:30 p.m., said Traffic Services Sgt. Jeff Redden.

The cyclists pedaled down the expressway for about 20 minutes and seven kilometres before being rounded up by police cruisers and directed toward the off-ramp at Dunn Ave, said Redden.

There were no collisions or injuries, but traffic was stalled as the bikers took up all westbound lanes and refused to leave, Redden said.

“It was a crazy idea. They came, and then like cattle they all went up the ramp and once they were up there, they realized there was a problem when they couldn’t get off the ramp.”

Some cyclists dismounted their bikes and climbed over a wall onto CN railway tracks to escape police, said Redden.

Redden said he had never seen anything like it. “It goes beyond common sense in saying its not a good idea...Everyone has their right to free speech and protest, but not in that manner.”

Redden said it did not appear to be an organized protest, but that several cyclists had placards demanding a bike lane along Bloor St. He believes it was related to the Critical Mass bike ride, which meets on the last Friday of every month.

Four cyclists who refused to leave the highway were arrested and charged under the Provincial Offences Act with cycling on a highway.

Redden said some of the cyclists dismounted their bikes, thrust them above their heads and ran at the officers.

Police had released everyone and traffic was moving slowly by around 8:30 p.m., about an hour after cyclists flooded the ramps.

Redden said there was no indication cyclists from the Toronto Criterium bike race happening nearby, were involved.

Yvonne Bambrick, of the Toronto Cyclists Union said she had no idea the event was occurring.

“Breaking the law is never a good idea ... It doesn’t strike me as a very safe thing to do.”

A Facebook group for the Toronto chapter of Critical Mass was abuzz today with posts about the controversial stunt.

Tory Law, 21 year-old cyclist and member of the group, confirmed the ride was organized by Critical Mass.

“I fully support Critical Mass’ cause, however the methods used to convey CM’s message last night is questionable indeed,” he wrote. “I think what CM did does portray a negative image; however, what other possible way is there to get attention?”