The Anonymous hacking collective has attacked San Francisco's BART (Bay Area Rapid Transit) website, and is calling for people to join a physical protest today.
The group is angered by BART's decision on Thursday to shut down cellphone service in an effort to avoid protests over BART police shootings.
On Saturday, Anonymous says it began a massive 'Black Fax' and 'E-Mail Bomb' action, aiming to fill every inbox and fax machine at BART with thousands of copies of a message complaining that the outage was unacceptable.
It brought down the www.bart.org website for six hours - "twice as long as they shut off the cell phones for," says Anonymous. The page is now showing an 'under construction' message, while the mybart.gov site appears to be still down.
After carrying out an SQL injection attack, the group's released a huge database of user information onto the Pastebin website, including emails, addresses and phone numbers.
In a statement, BART says it's doing all it can to defend itself from attack, and reassures users that its website is completely separate from the computer networks used to actually operate services.
Anonymous is also calling for a physical protest at the Civic Center Bart Station at 5:00 PM Pacific Time today - it wants people to turn up wearing 'bloodstained' clothing and to bring their cameras.
"We sincerely hope that this series of actions will serve as a warning to BART and every public organization in the USA to NOT engage in this sort of dangerous and human rights violating behavior," says Anonymous.
"You do not censor people because they wish to speak out against the wrongful things occurring around them. "
Not everybody agrees with Anonymous' actions.
"While it is understandable that people are upset with BART after the recent blocking of cell phone communications to prevent protesters from organizing, it is puzzling to me how exposing thousands of innocent people's personal information hurts BART more than it hurts transit users," says security expert Chester Wisniewski of Sophos.
"Users of rapid transit are certainly not the problem, and this simply takes a bad situation and makes it worse by creating even more victims."