A man has been arrested in connection with a series of suspected explosive packages that were intercepted this week and addressed to prominent Democrats and critics of President Donald Trump, multiple law enforcement sources said Friday.
Details about the arrest weren't immediately available.
Authorities intercepted all packages before they were delivered to their intended targets. None of the bombs detonated, and no one was injured.
Here's a breakdown of everything we've learned all week:
How many packages have been sent so far?
Authorities have intercepted at least 12 packages. They were addressed to:
Billionaire investor George Soros: One package, delivered to his home in New York. The package was reported to police Monday and rendered safe.
Hillary Clinton: One package addressed to her in New York but intercepted by the Secret Service on Tuesday evening. Clinton's home is in Chappaqua, but the Secret Service said the package was addressed to her in broader Westchester County.
Barack Obama: One package mailed to Washington but intercepted by the Secret Service at a screening facility. The Secret Service reported the existence of this package Wednesday.
Former Attorney General Eric Holder: This package, announced Wednesday, was addressed to him but sent to the Florida office of Democratic US Rep. Debbie Wasserman Schultz.
Democratic US Rep. Maxine Waters: Two suspicious packages were announced Wednesday: one intercepted at a congressional mail-screening facility in Maryland and a second one found at a postal facility in Los Angeles.
John Brennan: A "live explosive device," according to New York police Commissioner James O'Neill, was addressed to the former CIA director and delivered by courier to CNN's offices at the Time Warner Center in New York. It was discovered there Wednesday morning.
Actor Robert De Niro: A suspicious package sent to him at the Manhattan building where his production company is based was reported to police Thursday. It shows similarities to the other pipe bomb packages, sources said.
Former Vice President Joe Biden: Two packages intercepted at post offices in Delaware. Authorities reported their discovery Thursday.
Democratic US Sen. Cory Booker: A package addressed to Booker's Camden, New Jersey, office was found in Florida and is similar in appearance to the others, the FBI said Friday.
Former Director of National Intelligence James Clapper: A package addressed to Clapper and CNN was found at a New York City postal facility, a law enforcement official said Friday.
Where did they originate?
FBI Assistant Director William Sweeney declined to confirm the origin of the packages Thursday after reports that investigators believe some came from Florida.
Several of the packages went through a US Postal Service facility in Opa-locka, Florida, two law enforcement officials familiar with the investigation said.
"Some were obviously in the postal system," Sweeney said. "I'll leave it at that."
The Miami-Dade Police Department tweeted that its bomb squad and K-9 unit are providing assistance to federal partners at the Opa-locka mail facility.
"This assistance is as a precautionary measure," it said. "We cannot provide additional information at this time due to the active nature of this federal investigation."
Did the packages have any similarities?
The devices sent to Soros, Brennan and the top Democratic officials appeared to be pipe bombs, said Bryan Paarmann, FBI special agent in charge of the counterterrorism division in New York.
An initial examination shows they are rudimentary but functional and have similar construction. At least one contained projectiles, including shards of glass, a law enforcement official told CNN.
The packages were in manila envelopes with bubble-wrap interior, the FBI said, and each package had six American flag Forever stamps on the envelope. The devices had suspicious-looking packaging, and at least one had a timer that can be bought for a few dollars online and should be easily detected when mailed or delivered.
Were the pipe bombs designed to go off?
Authorities are wondering why none of the bombs went off, a law enforcement source told CNN's Evan Perez. In a statement, the FBI called them "potentially destructive devices."
The presence of what was believed to be pyrotechnic powder caused investigators to believe they could detonate, but it appeared the packages were handled and moved through the postal system without an explosion.
Based on an X-ray image of one of the devices, there appeared to be hazardous materials present, Anthony May, a retired Bureau of Alcohol, Tobacco, Firearms and Explosives investigator, told CNN's Brooke Baldwin. But it also appeared to be missing a crucial component for a functioning explosive device.
"What I'm not seeing is enough means to initiate this device, whether by design, whether by accident. I'm not seeing that," he said. "If I'm going by design, (if) it was designed that way, then the individual's motivation was simply to spread fear, instill fear."
Where are the packages now?
The devices sent to Clinton, De Niro, Obama, the CNN offices and Waters' East Coast office are either with the FBI or headed to the agency's lab in Quantico, Virginia. A controlled detonation was conducted on the device sent to Soros, while the one mailed to Waters' West Coast office was rendered safe by a bomb squad.
It's unclear where the others are.
A suspicious white powder found in an envelope along with the device sent to Brennan and CNN was tested and found not to be anthrax or other known agents, a source said. Additional tests will be done in the coming days.