Posted at 09:43 AM ET, 08/16/2011

BART service disrupted by protests at 4 San Francisco stations [PHOTOS, VIDEO]

BART police officers push back a protester at the Civic Center station in San Francisco on Monday. (Jeff Chiu - AP)
As British Prime Minister David Cameron clamps down on cellphone services across the pond, Americans are facing a First Amendment battle back home.

After authorities for San Francisco’s Bay Area Rapid Transit, or BART, blocked wireless signals in certain stations on Thursday, angry demonstrators organized by a hacker group disrupted service at four busy stations during Monday’s evening commute.

Dozens of protesters wore the Guy Fawkes masks made popular by the movie “V for Vendetta” as they carried signs and banners accusing BART officials of censorship.

The hacker group Anonymous also hacked the agency’s Web site, posting images of Guy Fawkes and personal information of thousands of the passengers.

The cellphone blackout had been an attempt to head off protests over the July 3 shooting death of Charles Blair Hill by BART police. Police say Hill came at them with a knife.

While First Amendment scholars say they can’t remember a time when a public agency clamped down on private communication in this way, BART's chief spokesman, Linton Johnson, told reporters: “There is a constitutional right to safety... A lot of people are forgetting the fact that there are multiple constitutional rights.”

BART officials said they knew of no arrests or injuries.

Watch footage of the protests below:

See more photos below:

A man is pulled off a commuter train at the Civic Center BART station in San Francisco on July 11 after climbing on top of it during a protest against the July 3 shooting by transit police of Charles Blair Hill. (Eric Risberg - AP)

An unidentified protester uses his cell phone at the Civic Center BART station on Monday. (Jeff Chiu - AP)

A screen shot taken from the Web site, a BART-sponsored organization, after it and other BART-related sites were hacked by Anonymous on Sunday. (AP)

Jevon Cochran, 21, demonstrates in the Civic Center station on Monday. (David Paul Morris - BLOOMBERG)

Police and passengers on the platform during the Monday demonstration at the Civic Center station. (ROBERT GALBRAITH - REUTERS)

A demonstrator dons a mask at Monday’s protest in San Francisco. (Justin Sullivan - GETTY IMAGES)

Protestors pretend to talk on phones to taunt a BART police officer at the Civic Center station on Monday. (Justin Sullivan - GETTY IMAGES)

By  |  09:43 AM ET, 08/16/2011

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