Authorities are investigating a series of suspicious packages sent to CNN and several prominent Democrats.
The packages apparently contained pipe bombs, officials said. No injuries were reported.
Lawmakers and media personalities demanded an end to aggressive, partisan rhetoric on Wednesday after the incident.
Law enforcement agencies investigate suspicious packages containing "potential explosive devices" that will be mailed to several prominent Democrats, including Hillary and Bill Clinton and former President Barack Obama, as well as CNN.
The devices were sent home to the Clintons late Tuesday, Chappaqua, New York, about 30 miles north of New York City and early Wednesday in Obama's Washington, DC office, according to the Secret Service.
CNN reported Wednesday night that the investigators tracked down an additional suspicious package that was apparently addressed to former Vice President Joe Biden. CNN's James Sciutto, who quoted two unnamed law enforcement officials, said the authorities considered the package to be a threat as it looked similar to the others this week.
Reuters later confirmed the message about the mailing to Biden.
"Packages were immediately identified as potentially explosive devices during routine post-screening procedures and handled appropriately as such," the Secret Service said in a statement on the first mailings. "The protectors did not receive the packages, nor was there a risk of receiving them."
CNN's New York newsroom was evacuated on Wednesday morning after a "suspicious package" was discovered in the post office with a device that appeared to be a pipe bomb, along with an "envelope containing white powder" that has just been tested said New York City Police Commissioner James O'Neill reporters.
The package was addressed to former CIA director John Brennan, reported CNN . Brennan, a contributor to NBC and MSNBC, does not work for CNN.
The explosive device sent to CNN headquarters It was said to have been sent by the same person or individuals who sent the packages to the Clintons and Obama, NYPD chief of anti-terrorism said. It is also expected that the same person or group will be behind a detonator sent to prominent Democratic donor George Soros earlier this week.
It is unclear what motivates the person or individuals to send the apparent explosive devices, although all the intended victims are frequently topics of President Donald Trump's anger. The president has repeatedly attacked CNN as a "fake news", jailed Hillary Clinton and claimed to be the victim of a Soros-Democrat conspiracy.
All packages studied had Rep. Debbie Wasserman Schultz (D-Fla.), The former Democratic National Committee chairman, was listed as the sender of the return, although her name was misspelled as "Shultz," the FBI confirmed.
A suspicious package found Wednesday at Wasserman Schultz's office in Sunrise, Florida, had been addressed to former Attorney Eric Holder, but was forwarded to her address on the return notice.
Wasserman Schultz made a statement condemning the attempted use of force and saying it was " deeply disturbed by the way [her] name was used."
A suspicious package addressed to Rep Maxine Waters (D-Calif.), Also intercepted at a convention post office in Capitol Heights, Maryland, confirmed her office to HuffPost
"I was informed by the US Capitol Police that my office in Washington, DC, that The target of a suspicious package was that was referred to the FBI, "Waters said in a statement. "I clearly condemn all acts of violence and acts of terrorism."
However, the FBI did not mention this package on Wednesday afternoon in an update on the situation.
New York Governor Andrew Cuomo (D) also said a device "was sent to his Manhattan office, but a NYPD sergeant confirmed to HuffPost that it was not a suspicious package, but a letter and a USB Drive that contained electronic files belonging to the violent right-wing group Proud Boys and posed no threat.
Several news agencies initially reported that a separate package had been sent to the White House, and the Secret Service said the reports were wrong. [Explanation:AtthattimetheSecretServiceinterceptedTWOsuspiciouspackets-oneinNewYorkandoneinWashingtonDCReportsofathirdinterceptedpackettotheWHarefalseWerefertoourstatement:https://tco/lJdTn04KmI
– US Secret Service (@SecretService) October 24, 2018
New York Mayor Bill de Blasio has sharply criticized the attempts as a terrorist
"What we saw here today was an attempt to terrorize, clearly an act of terror trying to undermine our free press and leaders in this country with acts of violence," he said. "I want to make it clear that the people in New York are not intimidated, we will undauntedly lead our lives because the concept of terrorism is about to change us and we will not allow that."
The White House said "United States intelligence agencies and other law enforcement agencies are investigating and will take all appropriate measures to protect anyone threatened by these cowards."
"We condemn the recent violent attacks on President Obama, President Clinton, Secretary Clinton, and other public figures," White House spokeswoman Sarah Huckabee Sanders said in a statement. "These acts of terrorism are despicable, and every person in charge will be held accountable to the fullest extent of the law."
First, Trump did not speak personally about the situation, but tweeted: "I fully agree!" Together with a statement by Vice President Mike Pence, who condemned the attempted attacks.
Trump later condemned the attempted attacks on the press.
"In these times we must unite, we must come together and send a very clear, strong and unequivocal message that there is no room for action or threats against political violence in the United States of America," he said. "We are extremely angry, upset, unhappy with what we experienced this morning and we'll get to the bottom of it."
CNN President Jeff Zucker beat the White House for its repeated attacks on the media as a result of the bomb threats
"The White House is completely unaware of the seriousness of its continued attacks on the media," he said Sugar on Wednesday afternoon in a statement. "The President and especially the White House press officers should understand their words are important, and so far they have not shown understanding."
Hillary Clinton thanked the Secret Service on Wednesday. Although she did not name Trump in her remarks about the suspicious package, she noted the "deep divisions" that plagued the country.
"We are fine, thanks to the Intelligence men and women intercepting the package" It is a disturbing time, is not it? "Added Hillary Clinton of Miami," It is a time of deep divisions and we have to do everything to bring our country together. "
Sebastian Murdock contributed to the coverage.
This is a developing story, please search for updates.