Aug. 2 (Bloomberg) -- New York ``Hercules'' police teams wearing body armor and toting submachine guns surrounded the New York Stock Exchange today, one of five buildings in New York, Washington and New Jersey cited by U.S. officials as likely targets of an al-Qaeda bomb plot.

Amid the clampdown, U.S. Senator Charles Schumer and NYSE Chief Executive John Thain stood for about 20 minutes at the Broad and Wall streets entrance of the exchange, greeting employees as they passed with their green identification cards.

``The security has been unbelievable,'' said Brian Teague, 21, a University of Connecticut student working as a summer intern for the exchange. ``The police are everywhere.''

Thain repeatedly told reporters that today was ``business as usual'' at the 212-year-old institution, which closed for four trading days after the attacks of Sept. 11, 2001. Schumer said he and Thain were ``there to show solidarity with the people of the New York Stock Exchange and the people of New York City. New Yorkers are a plucky group.''

U.S. Homeland Security Secretary Tom Ridge announced the alert and identified the potential targets yesterday after intelligence authorities discovered al-Qaeda plans that Ridge described as unusually specific. The plot aims at major attacks on financial institutions symbolic of U.S. influence in the global economy, according to Ridge.

U.S. Treasury notes rose today, pushing yields to the lowest in more than a week, after the U.S. government warning on the threat.

Elsewhere in New York, the sense of alert was evident as police shut down midtown Manhattan streets around 8 a.m. due to a report of a suspicious package that turned out to be harmless. Officers implemented ``code orange'' measures and closed the intersection of Lexington Avenue and East 57th Street for more than an hour.

Citigroup Building

At Citigroup Center, one of the other four named targets, a platoon of police cars, their lights flashing and motors running, lined the Lexington Avenue side of the building at about 8 a.m., accompanied by foot police, some of them with dogs and sub-machine guns. Officers stopped traffic while the cars were assembling.

Foot patrolmen also lined the front of the Central Synagogue, which is one block to the north of Citigroup's 59-story tower on Lexington. New York-based Citigroup is the world's biggest financial services company.

Security was also tightened in Washington around the two buildings there identified by the U.S. Department of Homeland Security as possible targets: the offices of the World Bank and the International Monetary Fund, which are as close as two blocks from the White House.

In Newark, officers cordoned off the headquarters of Prudential Financial Inc.

Ferry Riders Searched

On the Seastreak Ferry, which carries commuters from Highlands, New Jersey, in Monmouth County to Pier 11 at the foot of Wall Street, there were local police conducting random searches this morning as commuters boarded.

Pakistan said a detained Islamic extremist suspect who may be a computer expert gave information to its security agencies about terrorist attacks planned by the al-Qaeda network.

The unidentified individual was arrested in a separate raid than the one in Gujrat last month in which Pakistani security officers arrested several suspected members of al-Qaeda, including Ahmed Khalfan Ghailani, Information Minister Sheikh Rashid Ahmed said by telephone from the capital Islamabad.

Ghailani, a Tanzanian, was wanted for his alleged role in the 1998 bombings of the U.S. embassies in Kenya and Tanzania.

To contact the reporter on this story: David M. Levitt in New York at dlevitt@bloomberg.net.

Last Updated: August 2, 2004 10:14 EDT