The “thugs” behind attempted pipe bomb attacks on CNN’s headquarters, the Clintons and Barack Obama committed an “act of terror”, New York City’s mayor has said.
Mayor Bill de Blasio branded the shocking incidents as an effort to terrorise and to “undermine our free press and leaders of this country through acts of violence”.
An investigation into the attempted attacks is under way and is “of the highest priority”, the FBI said after at least five suspicious parcels were intercepted on Wednesday.
There has been no immediate claim of responsibility.
A package addressed to Mr Obama was intercepted by Secret Service agents in Washington. A further package, confirmed to be a viable bomb, was intercepted by an aide at the Clintons' home in Chappaqua, New York.
Investigators believe the devices are of the same type that were sent to billionaire philanthropist and Remain-backer George Soros, a prominent Democratic Party donor.
The HQ of news broadcaster CNN was also evacuated after a suspicious package - later confirmed to be a pipe bomb - was found in its post room.
Police told NBC News that all four packages sent to the Time Warner Centre, Obama, Clinton and Soros are "nearly identical."
An unnamed official has also said the pipe bombs were packed full with shards of glass and powder.
John Miller, the New York City police deputy commissioner for intelligence and counterterrorism, told a news conference: "So far the devices have been what appeared to be pipe bombs.”
He added: "This clearly is an act of terror attempting to undermine our free press and leaders of this country through acts of violence," New York Mayor Bill de Blasio told a news conference.
New York Governor Andrew Cuomo also labelled the delivery of the suspicious packages an act of intimidation perpetrated by "terrorist thugs."
"What they are trying to do is scare us and destabilize us, and we will not allow that to happen," he said.
De Blasio later dismissed social media postings suggesting that the packages were a liberal hoax, telling CNN, "This is the real thing."
"The bomb that was removed from the building right by here was a serious bomb ... No, this is the real thing," de Blasio said.
Hillary Clinton said her family is "fine" after the device was found.
She said her "family is fine thanks to the men and women of the secret service who intercepted the package addressed to us long before it made its way to our home.
"Every day we are grateful for their service and commitment and never more than today. But it is a troubling time, isn't it."
The White House condemned "the attempted violent attacks recently made against President Obama, President Clinton, Secretary Clinton, and other public figures".
Donald Trump later condemned the bomb threats, saying threats of political violence have no place in the US. He promised a full investigation.
The president said: “The full weight of our government is being deployed to conduct this investigation and bring those responsible for these despicable acts to justice. We will spare no resources or expense in this effort.”
