Attorney General Jeff Sessions says a suspect has been arrested in connection with mailing 12 suspicious packages.
Sessions says Cesar Sayoc, 56, of Aventura, Florida, is being charged with five federal crimes, including the illegal mailing of explosive devices and threatening government officials.
FBI Director Christopher Wray said 13 IEDs were sent in the packages, and each mailing included 6 inches of PCV pipe, a small clock and potentially explosive material.
"These are not hoax devices," Wray said.
He said a fingerprint found on one of the packages led investigators to Sayoc. He said possible DNA evidence was found on another package.
The crude pipe bombs were addressed in recent days to former President Barack Obama as well as other high-profile Democrats, including former Secretary of State Hillary Clinton, a former U.S. attorney general, two Democratic Party members of Congress, and former Central Intelligence Agency Director John Brennan.
Federal authorities apprehended Sayoc just hours after the Federal Bureau of Investigation intercepted two more suspicious packages, one addressed to Democratic Senator Cory Booker, the other to former National Intelligence Director James Clapper.
Clapper said on CNN Friday morning he was not surprised he was targeted and said the incidents were "serious."
President Donald Trump vowed Friday that those responsible for mailing suspicious packages will be prosecuted to the "fullest extent of the law."
"These terrorizing acts are despicable and have no place in our country," Trump told an enthusiastic group attending the Young Black Leadership Summit at the White House. "We must never allow political violence to take root in America."
In a tweet earlier Friday, however, he referred to the investigation as "this `bomb' stuff," which he blamed for taking focus away from the upcoming midterm elections. He also complained his critics were blaming him for heated political rhetoric.
Federal investigators searched a massive mail sorting facility in Florida late Thursday, after determining that at least one of the pipe bombs was processed there.
All of the "suspected explosive devices" were taken to the Federal Bureau of Investigation's laboratory at the U.S. Marine Corps base in Quantico, Virginia, said New York City Police Commissioner James O'Neill.