Major U.S. cities raise vigilance
No immediate plans to raise threat level
Department spokesman Brian Roehrkasse said, however, that there were no immediate plans to raise the nation's threat level.
"We do not have any intelligence indicating this type of attack is planned in the United States," Roehrkasse said.
The Homeland Security Department asked authorities in major cities for "continued vigilance" of their transportation systems, Roehrkasse said.
CNN showing video from a cell phone inside one of the subway cars.
I'm really sick and tired of this defensive posturing about alert levels from our government. If we killed the enemies at home and don't let them in, then we won't have to worry about alert levels. I want to see FBI round ups and firing squads.