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WASHINGTON — The FBI and military authorities said Monday that they were investigating a half-dozen suspicious packages containing explosive components, sent to military and intelligence addresses in the Washington area.

The first was discovered Monday morning at the National Defense University, at Fort McNair in southwest Washington. It was quickly rendered safe, the military said.

One of the packages was sent to the National Defense University, at Fort McNair in Washington. Reuters

By day's end, law enforcement officials said, similar packages turned up at other military and intelligence locations — six in all, including the CIA's mail-sorting facility, a White House mail-sorting facility in suburban Washington, a U.S. Navy facility in Dahlgren, Virginia, and two facilities at Fort Belvoir, Virginia — the National Geospatial-Intelligence Agency and another defense university.

Law enforcement officials said the packages were sent through the mail. Some included letters that one official described as disturbed and rambling. And each time, they said, the packages were quickly rendered safe.

Several federal officials said they did not believe that any of the packages came from Mark Anthony Conditt, who caused three weeks of terror in Austin, Texas, by placing and sending functioning bombs there.

The packages are being examined by the FBI to see if they're the work of the same person or persons, and to determine whether they were working devices or hoaxes meant to look real.