Authorities have stepped up security in Washington D.C., New York City, and other parts of the United States after U.S. officials warned of an al-Qaida plot to attack key financial centers.
The government listed five potential targets, including the New York Stock Exchange, and the World Bank and International Monetary Fund buildings in Washington.
In New York today (Monday), police have shut down two tunnels leading to the city's financial district. In Washington, security personnel are inspecting large vehicles that come near the World Bank and IMF.
And in Newark, New Jersey, workers have erected metal fences around the Prudential Building -- one of the two other suspected targets along with New York's Citigroup Center.
Briefing reporters Sunday, Homeland Security chief Tom Ridge said the warning is based on specific information coming from multiple intelligence sources.
A senior intelligence official says al-Qaida gathered detailed information about the buildings, such as whether they have structural features that would make them likely to withstand an explosion.
Despite the heightened alert, officials are urging Americans to go about their business as usual.
Information for this report is provided by AP.