The New York Police Department’s Total Containment vessel arrives yesterday at the scene of a suspicious package received in New York. Image Credit: AP

New York: Federal agents searched a mail facility near Miami on Thursday night as they raced to find who sent 10 pipe bombs to prominent Democrats and critics of Donald Trump.

The homeland security secretary, Kirstjen Nielsen, told Fox News: “Some of the packages went through the mail. They originated, some of them, from Florida,” she said. “I am confident that this person or people will be brought to justice.”

On Thursday the FBI was also examining devices sent to former US vice-president Joe Biden and actor Robert De Niro. Two packages for Biden were intercepted in Delaware, according to the FBI, while another was received at De Niro’s offices in New York City. Investigators said they matched those sent to former president Barack Obama and several other Democrats this week, which contained pipe bombs.

The new discoveries mean that eight high-profile Trump critics have been sent a total of 10 packages so far. All the packages were intercepted and removed without detonating, and no injuries were reported.

A police bomb squad and canine units joined federal investigators examining a mail distribution centre at Opa-Locka, north-west of Miami on Thursday, said Miami-Dade county police. The sprawling warehouse, where authorities believe several of the parcels were processed, appeared to remain in operation during the search.

The New York police commissioner, Jim O’Neill, said at a news conference on Thursday afternoon that investigators were also following up on tipoffs from the public. “We are discovering things by the hour,” said O’Neill.

Officials said people thought to be at risk of receiving the devices had been identified, warned and given help screening their mail. John Miller, the NYPD’s deputy commissioner for intelligence and counter-terrorism, said of the packages: “We’re watching where they go.”

Those targeted so far appeared to share a record of clashing with Trump and becoming figures of loathing among some of his supporters.

Biden has stridently condemned Trump’s presidency since leaving office, while De Niro received a standing ovation at the Tony awards in New York in June for a speech criticising the president. A spokesman for Biden declined to comment.

Trump and White House officials on Thursday rejected suggestions that he bore any responsibility for the circumstances around the attempted bombings, instead claiming that the media was to blame for America’s inflamed politics.

“A very big part of the anger we see today in our society is caused by the purposely false and inaccurate reporting of the mainstream media that I refer to as fake News,” Trump tweeted . “It has gotten so bad and hateful that it is beyond description. Mainstream media must clean up its act, FAST!”

One of the suspect packages, which police said contained a “live explosive device”, was sent to the New York studios of CNN, one of the most frequent targets of Trump’s campaign to discredit the media. The channel’s journalists were evacuated.

Speaking at an event in Washington on Thursday, Trump’s attorney general, Jeff Sessions, said FBI agents were “working around the clock” to find the person or people responsible for the bombs.

“Across this administration - across this country - we condemn these actions in the strongest possible terms and we are determined that justice will be done,” said Sessions.

In addition to Obama, his former secretary of state Hillary Clinton, former CIA director John Brennan and former attorney general Eric Holder were all sent packages containing pipe bombs, according to US authorities. Brennan’s was sent to CNN, where he has appeared as a commentator after leaving the government.

Congresswoman Maxine Waters of California was sent two packages and George Soros, a wealthy donor to liberal causes, received one in the mailbox of his New York home. Both are frequently derided by Trump and his Republican allies.

The packages were being analysed by the FBI at its laboratory in Quantico, Virginia. At least five of the packages, including the one sent to Soros, were in matching envelopes with similar computerised labeling and stamp arrangements.

Investigators were seeking forensic clues left on the unexploded packages and following other leads. CNN reported that the package found at its offices appeared to have been delivered by a courier. Others were sent through the US postal service.

X-ray photographs leaked to the media suggested that at least some of the packages contained pipes packed with explosive powder along with shrapnel such as pieces of glass. Andrew Cuomo, the governor of New York, said on Thursday that the devices were viable bombs.

Officials said the package at De Niro’s offices, in Manhattan’s Tribeca section, was discovered when a security guard from the building saw images of the other packages on television news bulletins on Wednesday evening. The guard, a retired NYPD detective, recalled processing a similar envelope at work. He called the bomb squad, which carried out an early-morning operation on Thursday to remove the package.

Philip Bartlett, the inspector in charge of the US Postal Inspection Service, said investigators searching through mail facilities across the US had found no additional suspect packages in the eight hours before 4pm on Thursday.

As the country’s November 6 midterm elections grew closer, there was mounting anger among some Democrats that Trump refused to tone down his rhetoric and declined to alter his schedule of political rallies to focus on what they termed a terrorist attack.

Charles Schumer and Nancy Pelosi, the Democratic leaders in Congress, said Trump’s condemnations of the attempted bombings rang hollow while he continued making remarks such as his praise for a congressman who physically assaulted a Guardian reporter last year.

“Time and time again, the president has condoned physical violence and divided Americans with his words and his actions,” they said in a joint statement.

But Sarah Sanders, the White House press secretary, told reporters: “The president is certainly not responsible for sending suspicious packages, any more than Bernie Sanders was for a supporter shooting up a baseball practice.”

In June last year, James Hodgkinson, a former volunteer for Bernie Sanders’ campaign for the Democratic presidential nomination, opened fire on Republican congressmen at a baseball training session in Virginia, seriously wounding Steve Scalise of Louisiana.

Trump has pushed conspiracy theories about Obama, Clinton and Soros, and led angry denunciations of Waters, who faulted his response to the death of a soldier in her district. Bernie Sanders, an independent senator for Vermont, has not made comparable remarks about Scalise or other Republicans.

Trump condemned the attempted bombings on Wednesday and said unity was needed in the US. But within hours at a campaign rally he was attacking the media for negative coverage.

Brennan, the former CIA director, said on Thursday that Trump’s critics “will not be intimidated into silence” and, rejected the president’s attempts to blame journalists for increased public anger and violence in the US.

“Stop blaming others,” Brennan said on Twitter . “Look in the mirror. Your inflammatory rhetoric, insults, lies, & encouragement of physical violence are disgraceful. Clean up your act....try to act Presidential. The American people deserve much better.”