A few dozen protesters turned out on Monday for a San Francisco rally organized by the hacker group Anonymous to protest alleged police brutality and what they called anti-free speech tactics by authorities.

Bay Area Rapid Transit, the commuter train service in the San Francisco area, shut down cell phone networks in some stations on Thursday to stop a demonstration over the fatal shooting of a man by police last month.

The cell phone shut-down drew a new wave of criticism, spurring the Monday rush hour action.

This was a complete silencing of the people. said Carlos Wilson, a 41-year-old gay rights activist who came to protest police brutality and the shut-down of the mobile phone network last week.

The Monday protest ended just before 5:30 p.m. local time, when authorities shut down the Civic Center station.

Police said there were no arrests, although officers arrived dressed in riot gear.

Cell phone service was left on in the station during the action, and some protesters took that as a sign of victory.

I have more cell service now than usual on BART. I think what they did last time was an empty threat. I have full bars, said Beck Simmons, a 21-year-old student, who was protesting the police shooting.

Anonymous, a loosely knit group that has attacked financial and government websites, had called for protesters to descend on the station at 5 p.m., and media widely publicized the plan.

Would-be protesters were encouraged to download software for short-range mobile-to-mobile messaging, in case the in-station networks are shut down again.

BART said that a website for its users, myBART.org, had been hacked over the weekend, and contact information from at least 2,400 people had been stolen.

(Writing by Peter Henderson; Editing by Dan Whitcomb and Jerry Norton)