SAN FRANCISCO (CBS SF) — A cyclist riding in San Francisco’s Critical Mass last week allegedly broke the window of a car trying to pass through the crowd.

A YouTube video captured the tense scene at about 8 p.m. Friday in the Marina District.

The video shows a group of cyclists riding against traffic on Marina Boulevard as a Zipcar station wagon creeps ahead of a group of halted cars. One cyclist stops in front of the moving car and yelled “Stop that!” as other cyclists begin to surround the car.

“You f–ing hit my bike,” the original cyclist is heard saying as others join in to confront the driver.

The driver tries to back up and maneuver around the group but is blocked again. As the driver begins to make her way past the group, one cyclist hits and breaks the driver side window with a U-lock.

Warning: Video Contains Some Profane Language

San Francisco police are now looking for the window-smashing cyclist, but no police report had been filed as of Monday.

In a statement emailed to CBS SF, a Zipcar spokeswoman said they are aware of the incident but were unable to comment on specifics.

On its FAQ page, Critical Mass organizers say: “We oppose anti-social behavior of all kinds, and when we see bicyclists harassing motorists or picking fights we confront them. We promote an open approach that invites motorists to join us and does not assume the worst about people we don’t know. We have also circulated dozens of flyers over the years criticizing bad behavior, with some success.”

A San Francisco bike group posted the video, sparking anger among many in the community.

https://www.facebook.com/groups/SanFranciscoBikeRideCrew/permalink/875534572542607/

Critical Mass, a monthly protest ride in over 300 cities around the world, has mostly negative reviews on Yelp.

“I am an avid cyclist. But I HATE Critical Mass,” Mika G. of San Francisco posted. “I hope people don’t think all cyclist are that ignorant of people’s need to get somewhere.”

But Ron B. of San Francisco sees it differently. “One of the great SF traditions! I love all these negative reviews; just makes me laugh. Try using your bike or public transportation during the next mass, and you won’t have any problems!”