Two more suspicious packages have been found as US authorities hunt for the sender of a series of devices addressed to prominent critics of Donald Trump.
They were intercepted as investigators scramble from coast to coast to locate the culprit and motives behind a bizarre plot aimed at critics of the president.
The discoveries brought to 12 the total number of devices addressed in recent days to Democratic figures including former president Barack Obama, ex-vice president Joe Biden and Hillary Clinton. The FBI said the package to Mr Booker was intercepted in Florida, and the one discovered at a Manhattan postal facility was addressed to Mr Clapper care of CNN.
Mr Clapper said he was not surprised to be targeted, and described the mail bombs as “definitely domestic terrorism”. He described the situation as “serious”, but insisted it was “not going to silence the administration’s critics”.
He stressed that he did not want to suggest any direct link between Mr Trump’s rhetoric and the packages, but the president should bear responsibility for the “coarseness and uncivility of the dialogue in this country”.
An earlier package had been sent to former Obama CIA director John Brennan care of CNN in New York.
Investigators are analysing the crude devices to reveal whether they were intended to detonate or simply sow fear before elections next month.
Law enforcement officials said the devices, containing timers and batteries, were not rigged like booby-trapped package bombs that would explode on opening, but they were uncertain whether the devices were poorly designed or never intended to cause physical harm.
A search of a postal database suggested some may have been mailed from Florida, one official said. Investigators homed in on a postal facility in Opa-locka, where they believe some of the packages originated.
Homeland Security secretary Kirstjen Nielsen acknowledged that some of packages originated in Florida.
New details about the devices came as the mail bomb scare spread nationwide, drawing investigators from dozens of federal, state and local agencies in the effort to identify one or more perpetrators.
The targets have also included CNN and Democrat Maxine Waters of California. A common thread is their critical words for Mr Trump and his frequent criticism in return.
The president claimed on Friday that he was being blamed for the mail bombs, complaining in a tweet: “Funny how lowly rated CNN, and others, can criticize me at will, even blaming me for the current spate of Bombs and ridiculously comparing this to September 11th and the Oklahoma City bombing, yet when I criticize them they go wild and scream, ‘it’s just not Presidential!’”
Details suggested a pattern — that the items were packaged in manila envelopes, addressed to prominent Trump critics and carried US postage stamps. The devices are being examined by technicians at the FBI’s forensic lab in Quantico, Virginia.
The packages stoked nationwide tensions as voters prepare to vote on November 6 to determine control of Congress — a campaign both major political parties have described in near-apocalyptic terms.
Even with the sender still unknown, politicians from both parties used the threats to condemn a toxic political climate and lay blame. “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,” Mr Trump said on Twitter.
“It has gotten so bad and hateful that it is beyond description. Mainstream Media must clean up its act, FAST!” Mr Brennan fired back: “Stop blaming others. Look in the mirror. Your inflammatory rhetoric, insults, lies, & encouragement of physical violence are disgraceful. Clean up your act….try to act Presidential.”
The explosive devices were packed in envelopes with bubble-wrap interiors bearing six American flag stamps and the return address of Florida representative Debbie Wasserman Schultz, the former chairwoman of the Democratic National Committee.
The bombs seized on Wednesday were about 6in long and packed with powder and broken glass, according to a law enforcement official who viewed X-ray images. The official said the devices were made from PVC pipe and covered with black tape.