With every intercepted pipe bomb and suspicious package, fear spread from New York to Washington, Florida, Delaware and California. The devices stashed in manila envelopes and mailed nationwide targeted top Democrats, critics of President Donald Trump and CNN.
None of the bombs detonated, and no one was injured, but the FBI has said additional packages may have been mailed to other locations.
Investigators believe some of the packages might have originated in Florida, according to a law enforcement official. A second law enforcement official told CNN on Thursday that federal investigators were in Florida, chasing down leads.
Here's a breakdown of what else we know:
Democrats, Trump critics and CNN received the packages
The pipe bombs were sent to a mix of office and residential addresses, and appeared to target some of the people Trump criticizes frequently. Most of the packages had a similar return address: that of US Rep. Debbie Wasserman Schultz, D-Florida, whose last name was misspelled. There is no information to suggest she sent the packages.
Barack Obama: The package sent to the former President was intercepted in Washington during routine mail screening procedures, the Secret Service said.
Bill and Hillary Clinton: The package was addressed to their residence in Chappaqua, New York, and was intercepted Tuesday night by the Secret Service during routine mail inspection.
Eric Holder: The package was addressed to the former attorney general but sent to the Florida office of Wasserman Schultz, whose return address was on the package.
Maxine Waters: A suspicious package addressed to the Washington office of the Democratic congresswoman from California was intercepted at a congressional mail-screening facility in Maryland, and a second package addressed to Waters was found at a postal facility in Los Angeles. It matches the description of those sent to the other officials.
John Brennan: The "live explosive device" was delivered by courier to CNN's offices at the Time Warner Center in New York and was addressed to the former CIA director. New York police said an envelope containing white powder also was found as part of the device's original packaging. A law enforcement official told CNN the device was sent to the FBI's lab in Quantico, Virginia, for further testing. The white powder was tested and initially deemed not to be anthrax or other known agents, the source said. Additional testing will continue.
Joe Biden: On Thursday, authorities discovered two packages at post offices in Delaware addressed to the former vice president, according to the FBI. At least one of them had been misaddressed and returned to sender, two law enforcement sources previously told Campbell and CNN's Brynn Gingras.
George Soros: A suspicious package found Monday appeared to be an explosive device targeting the billionaire investor, philanthropist and Democratic donor. It was rendered safe in Bedford, New York, a law enforcement source told CNN.
Robert De Niro: Around 4:45 a.m. Thursday, police responded to a report of a suspicious package received at a nonresidential building in New York's Tribeca neighborhood, New York police Lt. Thomas Antonetti said. The package was addressed to actor Robert De Niro, a vocal Trump critic, and has markings similar to the other pipe bomb packages recently mailed nationwide, two law enforcement sources told CNN. De Niro was not at the building Thursday morning, according to a source with direct knowledge.
Authorities are investigating leads in Florida
In a press conference on Thursday, FBI Assistant Director William Sweeney would not confirm the origin of the packages, despite reports that investigators believed some came from Florida.
"Some were obviously in the postal system," Sweeney said. "I'll leave it at that."
Here's what else we know about the investigation:
• Two law enforcement officials familiar with the investigation said authorities believed several packages went through a processing and distribution center in Opa-locka, Florida. The facility handles incoming and outgoing mail from South Florida, according to a US Postal Service employee.
• An FBI bomb truck left New York City Thursday morning, carrying the device that was sent to CNN, according to a law enforcement official familiar with the investigation. It was bound for the FBI laboratory at Quantico, Virginia, the official said.
• The suspicious white powder found in an envelope along with the device sent to John Brennan and CNN was tested and found not to be anthrax or other known agents, the source said. Additional tests will be done in the coming days.
• The source also told CNN authorities aren't giving credence to reports of an image of an ISIS flag on the device, suggesting they don't believe it's connected to international terrorism. The image appeared to be a spoof or a parody of an ISIS flag that has circulated on the internet, the source added.
• Other suspicious packages discovered in New York -- sent to the Clintons and De Niro -- were also on their way to Quantico Thursday afternoon, said John Miller, the Deputy Commissioner of Counterterrorism and Intelligence for the New York Police Department.
They came in similar packaging
The devices sent to Soros, Brennan and the 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 bombs were unstable and could have been set off by handling, sources said.
The packages are in manila envelopes with bubble-wrap interior, the FBI said. 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.
The bomb maker wanted to create fear, expert says
The bombs were likely meant to be found and create panic, explosives experts say.
"Whoever is doing this is just trying to elicit a fear or disrupt something," said Ryan Morris, founder of Tripwire Operations Group, a company that provides explosives training to law enforcement and military officials. He had examined images of the devices sent to Soros and to CNN's New York offices.
"There are a multitude of more sophisticated methodologies that would have worked if they really wanted this to work," he added.
Authorities are wondering why none of the bombs went off, a law enforcement source told CNN's Evan Perez. In a press release, 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.
Anthony May, a retired ATF explosives investigator, told CNN's Brooke Baldwin that based on X-ray image of one of the devices, there appeared to be hazardous materials present. But it also appeared to be missing a crucial component for a functioning explosive device.
"I'm going to tell you straight up -- 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."
Trump blamed his opponents
Despite a chaotic day of what appeared to be an attempted large-scale attack on prominent Democratic figures, Trump pointed the finger at his opponents and the news media for the turbulent national political environment.
"Any acts or threats of political violence are an attack on our democracy itself. No nation can succeed that tolerates violence or the threat of violence as a method of political intimidation, corrosion or control, we all know that," he said Wednesday night.
He said the news media have a responsibility to set the national political tone. Then he resumed his attacks on Democrats, including one falsely claiming they are allowing immigrants to enter the county illegally.
On Thursday morning, the President tweeted that the media are to blame for much of the anger in society.