Potential explosives sent to homes of Barack Obama and Hillary Clinton, as CNN’s New York studios and Debbie Wasserman Schultz’s offices in Florida were evacuated

Pipe bombs have been sent to prominent critics of Donald Trump, authorities said on Wednesday, spreading terror in the US less than two weeks before the midterm elections.

Packages containing suspected explosives were sent to the homes of the former president Barack Obama and the former Democratic presidential nominee Hillary Clinton but intercepted by the US Secret Service.

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Another suspect package, addressed to the former attorney general Eric Holder, was discovered before reaching its target. The FBI also reported finding two suspicious packages addressed to the Democratic congresswoman Maxine Waters. Federal investigators were additionally trying to track down a suspicious package they believe was addressed to Joe Biden, a US official told Reuters.

And CNN evacuated its studios in New York after what police called a “live explosive device” was found in its mailroom. The package was addressed to John Brennan, the former CIA director, who has repeatedly clashed with Trump.

On Wednesday night the packages were being analyzed by the FBI at its lab in Virginia.

The packages were found after the discovery on Monday of a bomb in a mailbox at the New York home of George Soros, the billionaire liberal donor. The FBI said that device and at least four others found so far were in matching envelopes with similar address labeling and stamps.

Son of George Soros calls bombs a threat 'to the future of American democracy' Read more

Some Democrats expressed fears that party figures were coming under attack in advance of the 6 November congressional elections. James O’Neill, the New York police commissioner, said the recipients may have been selected because of their opposition to Trump. “It is of concern to us,” O’Neill said.

An urgent search was under way for the person or people behind the bombs.

Bill de Blasio, the mayor of New York City, described the attempted bombings as “an act of terror”. Asked if he linked the incidents to Trump’s praise last week for the violent assault of a Guardian journalist, De Blasio said politicians must stop encouraging attacks on the media. “And that has to start at the top,” he said.

Speaking at an event in Florida, Hillary Clinton said the US was in a “troubling time” and condemned divisive rhetoric by politicians. “We have to do everything we can to bring our country together,” said Clinton. “We also have to elect candidates who will try to do the same.”

Brennan suggested that he may have been targeted because of his past criticisms of Trump. “His rhetoric, I think, too frequently fuels these feelings and sentiments that now are bleeding over into, potentially, acts of violence,” the former CIA director said during an event in Austin, Texas. “A lot of this rhetoric really is counterproductive, it is un-American, it is what a president should not be doing.”

Brennan added: “One could make an argument that it has emboldened individuals to take matters into their own hands. So when he compliments individuals who have in fact body-slammed others, or that he’s going to pay the legal bill of somebody who takes a swing at somebody, that can only be seen as encouragement and incitement.”

Trump said at the White House that he condemned the attempted bombings and that a “major federal investigation” to catch those responsible was under way. He followed this with a plea for unity during a midterms campaign rally in Mosinee, Wisconsin.

“Any acts or threats of political violence are an attack on our democracy itself,” he told the crowd. “We want all sides to come together in peace and harmony. We can do it … Those engaged in the political arena must stop treating political opponents as morally defective.”

The words are likely to ring hollow with his critics. In the 2016 presidential election, Trump branded his rival Clinton “Crooked Hillary” and relished chants of “Lock her up!” from supporters.

The president went on: “No one should carelessly compare political opponents to historical villains, which is done often, it’s done all the time, got to stop. We should not mob people in public places or destroy public property. There is one way to settle our disagreements. It’s called peacefully, at the ballot box.”

But he soon reverted to a familiar scapegoat. The media, he said, has “a responsibility to set a civil tone and to stop the endless hostility and constant negative and oftentimes false attacks and stories”.

Even so, a few minutes later, Trump asked: “By the way, do you see how nice I’m behaving tonight? Have you ever seen this? We’re all behaving very well and hopefully we can keep it that way, right?”

Several influential supporters of the president tried, without evidence, to dismiss the attempted bombings as a liberal hoax.

But the idea caught on in some online chatrooms nonetheless and a sign reading “Democrats fake news fake bombs” was quickly spotted amid supporters of the Republican candidate for the Florida governorship, Ron DeSantis, ahead of a debate against his Democratic challenger, Andrew Gillum, on Wednesday evening.

A chaotic Wednesday began with a statement from the Secret Service that said suspicious packages addressed to Obama and Clinton had been intercepted in New York and Washington. The agency protects the families of former presidents.

One package was discovered late on Tuesday “in the vicinity of the Clinton residence in Chappaqua”, about 25 miles north of New York City, according to the FBI. A second, addressed to Obama’s home in Washington, was found early on Wednesday morning.

Over the following hours, more packages and office evacuations were reported by other high-profile critics of Trump.

Emergency responders arrived at the Time Warner Center in Manhattan following an 911 call from CNN, which broadcasts from the building.

The station said the package was delivered by courier and addressed to Brennan, who briefly appeared on CNN as a commentator after leaving the CIA. In August, Trump stripped Brennan of his security clearance for criticizing his presidency.

The device was removed from CNN’s building and special operations officers were investigating. O’Neill, the New York police chief, said the package contained what “appeared to be a live explosive device” and an envelope of white powder.

This video has been removed. This could be because it launched early, our rights have expired, there was a legal issue, or for another reason. CNN broadcast interrupted by fire alarm due to bomb threat – video

Police in Sunrise, Florida, said soon after noon that a suspicious package was found at a district office for staff of Debbie Wasserman Schultz, the former Democratic party chairwoman.

The package was addressed to Holder, a US attorney general under Obama, but was redirected to Wasserman Schultz’s office after it apparently could not be delivered. Wasserman Schultz was also falsely listed as the sender on the packages for Brennan, Clinton, Obama and Soros, according to the FBI.

Another package intended for Waters was caught during a screening of mail for members of Congress at a facility in Maryland. Waters has frequently been lambasted by Trump since criticising his response to the death of a soldier from her constituency.

Soros, Clinton and Obama are three of the most prominent figures in Democratic politics and have for years been the subjects of attacks and conspiracy theories from Donald Trump and allies in the Republican party and rightwing media.

Matt Gaetz, a Republican congressman from Florida, last week falsely suggested that Soros, a billionaire financier and philanthropist, was funding the “caravan” of Central Americans currently traveling through Mexico toward the US.

Alexander Soros, George Soros’s son, said a wave of vitriol against his father was unleashed by Trump’s 2016 presidential campaign. In an article for the New York Times, he said of the attempted bombing: “I cannot see it divorced from the new normal of political demonization that plagues us today.”

CNN is frequently singled out by Trump even as he leads a campaign to discredit the media generally. Trump tweeted an animated video in 2017 of him wrestling the CNN logo to the ground.

Investigators were examining whether the devices on Wednesday matched one found on Monday at the home of Soros. According to US officials, that comprised a six-inch length of pipe loaded with explosive black powder. It was safely detonated.

Following brief speculation about yet another package, the Secret Service said in a tweet: “Reports of a third intercepted package addressed to the WH are incorrect.”

Reuters and the Associated Press contributed reporting