A city on alert

New York alerted to possible subway attack 'If you see something, say something,' mayor urges city residents MSNBC staff and news service reports Updated: 6:31 p.m. ET Oct. 6, 2005 NEW YORK - New York City police and Mayor Michael Bloomberg on Thursday alerted the city's residents to a possible terror threat to the subway system. They said information on the threat, which was passed on by the FBI, originated overseas, and was being evaluated for its credibility. However, they said it was specific enough about a target and timing to warrant advising subway riders to be vigilant in coming days. "We have never had before a specific threat to our subway system," said Bloomberg. "Suffice it to say that its importance was enhanced above the normal level by the detail that was available to us from the various intelligence agencies," he told a news conference with other city officials on Thursday afternoon. Officials told NBC that the informant said attackers would try to smuggle explosives onto the New York train system — possibly in baby carriages — in an imitation of the London and Madrid attacks, several sources told NBC. Stepped-up vigilanceAuthorities had already increased security in the subway system, said police Commissioner Raymond Kelly. He urged the public to report suspicious people or activities. Police planned to start looking through bags, briefcases, baby strollers and luggage in a large-scale search of the city's mass transit system. "If you see something, say something," urged Bloomberg. "Then the professionals will make an assessment." A homeland security official tells NBC News that though the source has "doubtful" credibility, the heightened security in NY is necessary out of an abundance of caution. The source has apparently given some accurate information in the past, and some inaccurate. The officials spoke on condition of anonymity because they were not authorized to discuss the matter. "We have done and will continue to do everything we can to protect this city," Bloomberg said. "We will spare no resource, we will spare no expense. We have increased our police presence on our subways." New York's security level remained at orange, the second-highest. It has been at that level since Sept. 11. An estimated 4.5 million passengers ride the New York subway on an average weekday. The system has more than 468 subway stations. The Associated Press contributed to this report. URL: http://www.msnbc.msn.com/id/9614242/