FLORIDA WAREHOUSE

Homeland Security Secretary Kirstjen Nielsen, in an interview with Fox News Channel, confirmed that Florida was the starting point for at least a portion of the bomb shipments.

"Some of the packages went through the mail. They originated, some of them, from Florida," she said. "I am confident that this person or people will be brought to justice."

A police bomb squad and canine units joined federal investigators on Thursday examining a US mail distribution center at Opa-Locka, northwest of Miami, Miami-Dade County police said.

The sprawling warehouse, where authorities believe several of the parcels were processed, appeared to remain in operation during the search, with tractor-trailer traffic continuing to and from the facility as police were seen walking around the loading docks.

On Wednesday, two days after the first package arrived at Soros' home, the FBI identified five more targets - President Barack Obama, former Secretary of State Hillary Clinton, former Attorney General Eric Holder, former CIA director John Brennan, and California Representative Maxine Waters. Two packages were found addressed to her.

Brennan's package was sent in care of the Manhattan bureau of CNN, where he has appeared as an on-air analyst.

On Thursday, the investigation widened with the discovery of three additional packages - two intended for former Vice President Joe Biden in his home state of Delaware and one for Hollywood actor Robert De Niro in Manhattan.