U.S. Homeland Security is advising those in New York City and Washington, D.C., to be on high alert after intelligence has revealed a specific and credible threat of a terrorist attack to coincide with the tenth anniversary of the Sept. 11, 2001 attacks on the World Trade Center and the Pentagon.

President Obama has reportedly been advised of the threat, which was determined by intelligence from Pakistan.

As we know from the intelligence gathered from the [bin Laden] raid, Al Qaeda has shown an interest in important dates and anniversaries, such as 9/11, Department of Homeland Security spokesman Matt Chandler said in a statement. In this instance, it's accurate that there is specific, credible but unconfirmed threat information.

In this instance, it's accurate that there is specific, credible but unconfirmed threat information, the department said. As we always do before important dates like the anniversary of 9/11, we will undoubtedly get more reporting in the coming days. Sometimes this reporting is credible and warrants intense focus, other times it lacks credibility and is highly unlikely to be reflective of real plots underway.

Regardless, we take all threat reporting seriously, and we have taken, and will continue to take all steps necessary to mitigate any threats that arise. We continue to ask the American people to remain vigilant as we head into the weekend.

The intelligence indicates that bridges and tunnels as well as car bombs could be involved in a planned attack, which has not been attributed to a specific person.

A U.S. official told NBC News that specific threat information came in very, very recently, but did not elaborate further on the timing.

U.S. counter-terror agencies are taking it very seriously, the official said. The federal government is coordinating with state and local agencies to make people aware of this potential threat.

This is being treated very seriously at all levels of government.