WASHINGTON, D.C. — Former President Jimmy Carter has been warned by law enforcement that he could be a potential target and should be on alert for a potential pipe bomb sent by mail, his spokeswoman told ABC News Thursday.

The warning comes after at least 10 explosive devices were sent to two former presidents, several high-ranking Democratic officials and the CNN offices in New York City.

Former Vice President Joe Biden and actor Robert De Niro are the latest public figures to be sent suspicious packages like those sent to Hillary Clinton, former President Barack Obama and others.

A total of nine suspicious packages have been found as of Thursday in what has become a domestic terrorism investigation, law enforcement sources told ABC News. At least five contained devices resembling pipe bombs, intended to maim or kill.

The packages were addressed to:

• Two addressed to former Vice President Joe Biden in New Castle, Delaware.
• Actor Robert Di Niro at his New York City film and television company.
• Hillary Clinton's home in Chappaqua, New York.
• The house of former President Barack Obama in Washington D.C.
• Former Attorney General Eric Holder. That package, which was one of the ones with Wasserman Schultz's return address, was sent back to her Florida office, according to the Associated Press.
• Two addressed to Democratic California congresswoman Maxine Waters in Washington D.C. and her office Los Angeles.
• CNN's New York City newsroom, addressed to former CIA director John Brennan and delivered by a courier.
• The home of billionaire philanthropist George Soros, who has donated to Democratic campaigns, in Katonah, New York.

LATEST Updates:

Of 10 "suspected explosive devices," six were found in either USPS or government mail facilities, according to Channel 2's Jamie Dupree.

AP source says a search of a mail database in the package bomb probe has pointed investigators toward Florida.

US postal official says investigators looking for other package bombs have found nothing in the last 8 hours.

Former President Jimmy Carter has been warned by law enforcement that he could be a potential target and should be on alert for a potential pipe bomb sent by mail, his spokesman said Thursday.

12:00 p.m.

Channel 2's Justin Gray in the D.C. Bureau says the Cannon House, which serves as the office building for the U.S. House of Representatives, was evacuated after an alarm went off. It is unclear why.

Police have since given the 'all clear' and let staffers back inside the building.

Evacuated House staffers outside Cannon pic.twitter.com/oi8blEeW8e

Cannon House Office Building being evacuated now. We don't know why pic.twitter.com/JJmnar9NlS

10:00 a.m.

President Trump is blaming the media for widespread divide in the county in his morning tweets:

“A very big part of the Anger we see today in our society is caused by the purposely false and inaccurate reporting of the Mainstream Media that I refer to as Fake News,” Trump said in a morning Tweet. “It has gotten so bad and hateful that it is beyond description. Mainstream Media must clean up its act, FAST!”

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