Bay Area transit agencies are certainly heeding the warning. This all stems from a year-long investigation that revolves around a 24-year-old airport bus driver.
Mass transit agencies like BART have been advised to step up patrols now that counter-terrorism officials have uncovered an alleged plot they believe involved detonating backpack bombs aboard New York City trains.
Afghan-born, Najibullah Zazi, 24, of Denver is said to be at the center of the plot. He appeared in court on Monday accused of lying to authorities. FBI agents say they secretly copied Zazi's computer and found a bomb recipe with nine-hand written pages of notes. Zazi reportedly admitted he was trained in explosives by Al Qaeda in Pakistan where he traveled twice in the last year.
"So when he was questioned about whether or not he knew anything about these handwritten notes and it was shown to him, he denied any knowledge," said New York Police Commissioner Ray Kelly.
Zazi's father Mohammed Zazi was also arrested, as well as Ahmad Afzali, an imam at a mosque in Queens. According to court documents, the imam was working with the FBI until he warned Zazi that agents were on to him. Despite these arrests, investigators believe more may be involved. Agents made no secret of their round the clock surveillance of key individuals and locations around a New York mosque.
"The NYPD and the FBI are still actively hunting down the bomb and the bomb making facility. They believe there's a garage or warehouse somewhere where the bomb parts are being stored," said former national security officer Richard Clarke.
As for mass transit agencies, they're counting on the public to report any suspicious activity.
"They can contact the train operator with intercom on the trains, they can call a station agent with the white phones that are in the stations, and of course they can call BART Police," said BART spokesperson Jim Allison.
In addition to New York City trains, authorities believe based on what they found on Zazi's computer, he also had interest in Grand Central Station, and football and baseball stadiums.