Several bombs have been posted to high-profile Trump critics in the US, including former president Barack Obama. A crude pipe bomb was sent to Mr Obama at his family home in Kalorama, Washington DC, and was discovered early on Wednesday. Just hours earlier, another bomb was found addressed to former secretary of state and Democrat presidential candidate Hillary Clinton at the home she shares with former president husband Bill in Chappaqua, New York.
Both families have their mail screened offsite and were not at risk of receiving the bombs, the Secret Service said. Mrs Clinton later said she and her family were “fine”, thanking the Secret Service and saying they had intercepted the explosive “long before it made its way to our home”.
Donald Trump said he was “extremely angry, upset and unhappy about what we witnessed this morning and we will get to the bottom of it”.
He said: “In these times we have to unify, come together and send one clear, strong, unmistakable message that acts or threats of political violence of any kind have no place in the United States of America.”
Democrat leaders criticised the US president, saying his condemnation of violence “rings hollow”.
Senator Chuck Schumer and Representative Nancy Pelosi said in a joint statement that Mr Trump had “condoned physical violence and divided Americans with his words and actions.”
They cited the president’s backing of a GOP congressman who “body-slammed” a reporter, his relationships with dictators and his handling of a neo-Nazi rally in Charlottesville as examples.
CNN’s New York offices were also targeted and the broadcaster’s worldwide president Jeff Zucker appeared to blame the Trump administration and its attacks on the media for inspiring the attacks.
He said: “There is a total and complete lack of understanding at the White House about the seriousness of their continued attacks on the media.
“The president, and especially the White House press secretary, should understand their words matter.
“Thus far, they have shown no comprehension of that.”
On Wednesday morning part of New York City had been shut down after a pipe bomb was found in the broadcaster’s mailroom.
It was accompanied by an envelope with white powder, which police said was being tested.
Live footage later showed the NYPD’s bomb truck taking the explosive to a police facility in the Bronx where it would be examined.
Police said the package had been addressed to former CIA director and Trump critic John Brennan, who has appeared on the cable news channel as a contributor.
Officers had been making contact with people at high-profile locations following the earlier bombs, telling staff what to look out for. They were at the Time Warner building when that device was discovered.
An explosive device was also sent to Mr Obama’s former attorney general Eric Holder, whose package was reportedly addressed incorrectly and re-directed to Florida congresswoman Debbie Wasserman Schultz who had been named as the return address.
A suspicious package was also received by California congresswoman Maxine Waters. On Monday a similar device was found at the New York home of billionaire George Soros, a major Democrat donor. But suspect packages sent to New York governor Andrew Cuomo and a newspaper in San Diego, which shares its building with Democrat senator Kamala Harris, were later revealed to have been false alarms. Bryan Paarmann, the FBI’s top counter-terrorism official in New York, said: “We will not rest until we stop these hazardous devices from being mailed and bring the individual or individuals to justice.”
He said the nation was going through a “painful time” and that people were “feeling a lot of hatred in the air”.