A suspicious package was sent to the Florida office of Democratic Rep. While briefing the media after the incident, New York Police Commissioner James P O'Neill said, "NYPD and our law enforcement partners responded to reports of a suspicious package at CNN".
CNN reported that the package sent to its headquarters came via courier, and some reports said the parcel found in Soros' mailbox upstate was hand-delivered. Just two days earlier, CNN's offices in NY were evacuated when the package for Brennan, addressed to him at the network, was found in the mailroom. Mr Brennan is a frequent guest on CNN.
"The Secret Service has initiated a full scope criminal investigation that will leverage all available federal, state, and local resources to determine the source of the packages and identify those responsible", the agency said in a statement. Another was found in a Los Angeles postal facility. Hours later, the Federal Bureau of Investigation announced it had found two similar packages in Delaware.
The discovery of the packages comes a day after another package containing an explosive device was found outside the home of billionaire philanthropist George Soros at his home in suburban NY.
None of the devices exploded, and no one was injured. The show had been focusing in on a suspicious package sent to the home of former President Bill Clinton and his wife Hillary.
CNN's Jim Sciutto and Poppy Harlow were on the air shortly after 10 a.m., conducting a live interview about the devices sent to political leaders when the whooping sound of an alarm went off.
What was in the packages?
Law enforcement officials said all the packages were similar: manila envelopes with bubble-wrap interior bearing six stamps and the return address of Florida Rep.
The packages sent to Mr Obama, Mr Brennan, Mrs Clinton, Ms Waters and Mr Holder all contained suspected pipe bombs. De Niro's office is located in the TriBeCa Film Center in lower Manhattan, and also includes an upscale restaurant and private screening room.
How have United States political figures responded? Philip Bartlett, inspector in charge of the U.S. Postal Inspection Service's NY division, said Thursday afternoon that the Postal Service had found nothing since early that morning, leaving the tally at 10 packages.
But he says the media "has a responsibly to set a civil tone and to stop the endless hostility and constant negative and oftentimes false attacks and stories".
Mrs Clinton called the packages a sign of deep political divisions in the U.S., and stressed the need for the country to be united.
The sources said Sayoc had a criminal history and also had ties to NY.
"There is a total and complete lack of understanding at the White House about the seriousness of their continued attacks on the media", said CNN president Jeff Zucker earlier.
"We must never allow political violence to take root in America and I'm committed to doing everything in my power as president to stop it and stop it now".
And on the other side of the spectrum, Republican congressman and House majority whip Steve Scalise was one of several people wounded in June 2017 by a rifle-toting left-wing activist who died in the ensuing shootout with police.
This is what we know about the targets, many of whom are regularly attacked by the president online and in speeches as he defends his election victory and achievements in office.
Police officers visited other "locations associated with the Soros family, his businesses", and then when the devices addressed to Clinton and Obama were discovered, "we really widened our outreach", Miller said.