Florida suspect charged over 13 bombs in mail

A Florida man was arrested and charged Friday with sending 13 explosive devices to critics of President Donald Trump in a days-long spree inflaming a polarized United States ahead of key midterm elections.

Cesar Sayoc, 56, of Aventura, who reportedly has a criminal past and ties to New York, was arrested outside a strip mall and a van, covered in pro-Trump stickers, was impounded.

He has been charged with five federal crimes, including mailing of explosives and threats against former presidents, Attorney General Jeff Sessions announced.

If put on trial and convicted, he faces up to 48 years in prison in what politicians on both sides of the aisle have condemned as domestic terrorism.

The Republican president congratulated law enforcement for what he called an "incredible, incredible job".

"These terrorizing acts are despicable and have no place in our country," Trump told an event at the White House. "But the bottom line is Americans must unify and we must show the world that we are united together in peace and love and harmony as fellow American citizens," he added.

In southern Florida, FBI agents and police swarmed the area around the strip mall in Plantation, where an AFP photographer saw a van covered in blue tarpaulin loaded onto a truck by authorities before being driven away.

Thirteen packages containing improvised explosive devices were sent to CNN, Hollywood star Robert De Niro and high-profile Democrats, including former president Barack Obama, Hillary Clinton, Senators Cory Booker and Kamala Harris and other figures loathed by the president's supporters.

Each of the homemade bombs included six inches of PVC pipe, a small clock, a battery, wiring and energetic material, defined by FBI director Christopher Wray as potentially explosive.

The first package was sent on Monday to the Bedford, New York of billionaire liberal donor George Soros. The most recent packages were intercepted on Friday in California, Florida and New York targeting Harris, Booker and former intelligence chief James Clapper, another prominent Trump critic.

The Clapper package, as with one sent on Wednesday to former CIA director John Brennan, were marked care of CNN, a television network often critical of the administration and long provoking Trump's ire.

US media reported that Sayoc was a registered Republican voter but the FBI said it was too early to publicly pronounce on any motive.

"It's too early at this stage for us to be discussing motivation in this particular case," Wray told a news conference. "We're concerned about people committing acts of violence under any motivation."

The US president earlier came under fire for his response to the spree, which politicians on all sides have branded domestic terrorism, with devices intercepted in New York, Maryland, Florida, Delaware and Los Angeles.

On Friday, shortly before news of the arrest broke, he complained that the packages were slowing momentum for his Republican Party ahead of the November 6 elections, remarks bound to enrage his opponents.

"Republicans are doing so well in early voting, and at the polls, and now this 'Bomb' stuff happens and the momentum greatly slows -- news not talking politics," Trump tweeted.

"Very unfortunate, what is going on. Republicans, go out and vote!"

Trump was also criticized for tempering calls for unity in the wake of the attacks, by lashing out at the press for stirring up "anger."

He recently endorsed the body-slamming of a reporter, routinely denounces the press as "fake news" and has leveled toxic remarks in the past against the pipe bomb targets.

Double Oscar winner and biting Trump critic De Niro on Friday urged people to vote in the midterms, one day after a device was discovered at the Manhattan offices of his production company.

"I thank God no one's been hurt, and I thank the brave and resourceful security and law enforcement people for protecting us," he said. "There's something more powerful than bombs, and that's your vote. People MUST vote!"

"This is definitely domestic terrorism," Clapper told CNN, saying Trump bore "some responsibility of civility in this country. He needs to remember that his words count."

The packages were sent in manila envelopes lined with bubble wrap, each stamped with approximately six postage stamps each bearing the picture of an American flag.

Each envelope listed Debbie Wasserman Schultz, former chairwoman of the Democratic National Committee, as the sender, and misspelt Florida as "Florids" according to the criminal complaint.

Wasserman Schultz told reporters in southern Florida that it was "devastating" and "deeply disturbing" to have had her name used.

"I've been told by the FBI that this is their highest priority and they're on top of it," she said.