File: Rep. Scott Rigell (R-VA) listens to the concerns of constituent. (Melina Mara/THE WASHINGTON POST)

This item has been updated.

RICHMOND — The district offices of two Virginia congressmen were evacuated Friday after they received mail with suspicious substances inside.

Rep. Scott Rigell’s (R) Virginia Beach office was evacuated Friday after a letter was opened containing an “unidentified substance,” his office said. In Chesapeake, Rep. Randy Forbes’s (R) staff also had to clear the building because of a package with “a flaky unidentified substance.” Both incidents are being investigated by law enforcement.

Federal government offices as well as those of many media outlets have implemented stricter security procedures since 2001, when a series of letters containing anthrax were mailed to a host of offices on Capitol Hill and elsewhere. The attacks killed five people, drawing particular notice because they came soon after the Sept. 11, 2001 terrorist attacks on New York and the Pentagon.

“The local authorities as well as the United States Capitol Police were alerted and the office was immediately evacuated,” Rigell’s office said in a statement.

“The Virginia Beach fire and police departments responded with great speed and the letter was removed. It will be analyzed to determine if the contents were harmful in nature. Since the staff member who opened the letter immediately put it aside once the substance was noticed, the subject and intent of the letter is not known.”

Forbes’s office said, “Capitol Police and local law enforcement were immediately notified and are at the scene. The Congressman was not at the office at the time the package was delivered.”

U.S. Capitol Police spokesman Ofc. Shennell Antrobus said the department “is working an active, open investigation with the Federal Bureau of Investigation, as well as local law enforcement, on this matter.”

A Virginia Beach Fire Department spokesman told the Norfolk Virginian-Pilot that the powdery substance found in Rigell’s office posed no immediate hazard but would be taken to a lab in Richmond for testing