At least seven packages have now been identified, and officials say they were packed with glass and “potentially destructive”.
Donald Trump has launched a new attack on the media – hours after bombs were sent to the offices of CNN and the homes of several high-profile political rivals.
The US president, who has labelled many reporters as “enemies of the people”, said the media has “a responsibility to set a civil tone and to stop the endless hostility”.
Speaking at a rally in Wisconsin ahead of the mid-term elections, he said “any acts or threats of political violence are an attack on our democracy itself”.
Officials have said the pipe bombs, which did not detonate and were intercepted before they reached the people they were addressed to, were packed with shards of glass.
At least seven suspicious packages have now been identified – with recipients including former president Barack Obama and Hillary Clinton, who stood against Mr Trump in 2016.
Billionaire financier George Soros, a frequent target of right-wing conspiracy theories, was the first to receive a “potentially destructive” package on Monday.
The FBI says it is also trying to track down a suspicious package that they believe was addressed to former vice president Joe Biden.
New York mayor Bill de Blasio said: “This clearly is an act of terror attempting to undermine our free press and leaders of this country through acts of violence.”
All of the targets are frequently criticised by right-wing politicians and pundits, including Mr Trump, who regularly describes CNN as “fake news”.
In a robust statement after the news network’s office in New York was evacuated for several hours, CNN president Jeff Zucker said: “The president, and especially the White House press secretary, should understand that their words matter. Thus far they have shown no comprehension of that.”
It comes after Mr Trump last week praised a Congress member for Montana who body slammed a Guardian journalist who asked him a question in 2017, with the president describing the politician as “a great guy, tough cookie”.
Mr Trump has called for peace and harmony in the wake of the attempted bombings, but Democratic leaders in Congress have said the president’s words have “rung hollow”.
In a statement, two senior Democrats said: “Time and time again, the president has condoned physical violence and divided Americans with his words and his actions.”
During his rally in Wisconsin, the president took a softer tone and called attention to “how nice I’m behaving tonight”.
The devices were made from PVC pipe about six inches long and covered in black tape, X-ray images showed.
The package that arrived at CNN was addressed to John Brennan, a former director at the CIA.
He said: “Unfortunately, I think Donald Trump, too often, has helped to incite some of these feelings of anger, if not violence, when he points to acts of violence or also talks about swinging at somebody from the press, the media.”
Investigators are now examining the explosive devices in the hope of finding forensic clues such as fingerprints and DNA which might enable them to identify the sender.
The first step will involve retracing the path of the packages through the US Postal Service, which uses a sophisticated imaging system which can determine the specific location of where packages were sent.
Larry Johnson, a former head of criminal investigations for the US Secret Service, said bomb makers usually leave evidence behind – adding it is highly likely that the person responsible has had a run-in with law enforcement in the past.
Source : skynews