An Anonymous-organized street protest in San Francisco started relatively peacefully on Monday afternoon but "turned chaotic around sundown," according to media reports. Dozens were arrested after dark as a protest that began relatively peacefully in the late afternoon turned ugly, with protesters reportedly throwing stink bombs at police and kicking in glass bus shelters.

The second round of protests organized by Anonymous over actions by Bay Area Rapid Transit (BART) authorities, Monday's activities initially seemed less fiery than the previous Monday's protest, when about 100 or more protesters gathered at downtown underground stations, forcing BART authorities and the SFPD to for several hours.

Authorities did Monday but the initial scene on the BART platform at Civic Center station was slightly surreal, with riot police, journalists, and other observers outnumbering actual protestors by perhaps 20-to-1 if not more.

BART has come under fire from free speech advocates and drawn the ire of the loose collective of online hackers and activists known as Anonymous for during a protest earlier this month over the shooting death of 45-year-old Charles Blair Hill by BART police in July.

BART-run websites have been targeted by hackers in recent weeks, while Bay Area-based members of the global hacktivist collective Anonymous have helped to organize live protests the past two Mondays.

The transit authority has claimed it shut down cell service for public safety reasons, attempting to prevent protest organizers from communicating and organizing via mobile devices in the face of disruptive and potentially dangerous gatherings at San Francisco underground stations.

But critics of the cell service shutdown say BART lacks the authority to cut off such communications and they have attacked the legal rationale espoused by BART spokespeople for doing so. The ongoing operation against BART has drawn support from hacktivists associated with Anonymous, civil libertarians, and Bay Area residents upset with July's shooting and other incidents of alleged brutality, including the killing of Oscar Grant by BART police officer Johannes Mehserle on Jan. 1, 2009.