Police flooding into NY subways after warning of jihad bomb attack

Uniformed police officers have flooded New York City's Penn Station, home to the Long Island Rail Road, following a warning from the FBI of a "plausible but unsubstantiated" threat of a terrorist bomb attack against the system during the holidays.
Law enforcement officials tell ABCNews.com, the plot involved a "Madrid-like attack," a reference to the synchronized bombing of the commuter rail system in Spain in March 2004 that killed 191 people.
Following the public release of the warning by the FBI and the Department of Homeland Security, officials in Washington made efforts to dampen public concern.
"There is nothing concrete to suggest this plot ever went beyond the aspirational or talking stage," said a U.S. official familiar with the intelligence that led to the warning.
Law enforcement officials told ABCNews.com the information was based on an FBI source who has proved "reliable and knowledgeable in the past."
Officials told ABCNews.com unspecified new information in the last 48 hours led to the public warning "out of an abundance of caution."
Congressman Peter King (R-NY), the top Republican on the House Homeland Security Committee, told the Associated Press "authorities have very real specifics as to who it is and where the conversation took place and who conducted it."...