Potential explosives were sent to prominent critics of Donald Trump on Wednesday.
Packages containing suspicious materials were sent to the homes of former Democratic presidential nominee Hilary Clinton, former president Barack Obama, among other politicians.
To some, the would-be-attacks came as no surprise amid the wave of hatred towards politicians and the media, sparked by the US President.
The news station CNN evacuated its New York studio on Wednesday after police said a 'live explosive device' was found in the mailroom. CNN said the package was addressed to John Brennan, the former CIA director, who has previously clashed with the US president.
The New York police commissioner, James O'Neill, told a press conference investigators suspected the recipients could have been targeted because of their opposition to Trump.
New York mayor, Bill de Blasio, was questioned by a reporter if the incidents were linked to the US President's praise of a Congressman last week for assaulting a Guardian journalist.
"At a time when there’s a lot of hatred and division, it does not make sense to exacerbate it. Let’s just say this, to all public officials of all partisan affiliations- Don’t encourage violence, don’t encourage hatred, don’t encourage attacks on media", De Blasio responded.
He added the way to stop violence is to" bring down the temperature, to end any messages about the use of violence against people we disagree with, and that has to start at the top".
Meanwhile, Hilary Clinton said the US was living in a “troubling time” and condemned hateful speech 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.”
Donald Trump shared the response of Vice President Mike Pence in condemning the attacks, calling them "cowardly actions".
Trump later said: “Acts or threats of political violence of any kind have no place in the United States of America.”
But he stopped short in addressing criticism of his own role in attacking news outlets and opposing politicians.
Just after Trump made the comments on Wednesday, his campaign manager apologised for a campaign email which attacked CNN.
The email cited CNN coverage of a Trump campaign rally and read: “I have some breaking news for CNN...That is the real America that exists outside of the liberal bubble. It’s time for us to give the media another wake up call from the American people.”
Campaign manager Brad Parscale said it was a “pre-programmed, automated message that was not caught before the news broke” and condoned violence "against anyone who works for CNN, or anyone else”.
But Wednesday is not the first warning about the current political climate. A previous explosive device sent to financier Geroge Soros on Monday led his son Alexander to write an op-ed in the New York Times. He called the incident " profoundly disturbing – as a threat not just to the safety of our family, neighbors, colleagues and friends, but also to the future of American democracy”.