Investigators search for person who sent mail bombs, motive

Media that I refer to as Fake News," Trump said on Twitter. "It has gotten so bad and hateful that it is beyond description. Mainstream Media must clean up its act, FAST!"

Former CIA Director John Brennan, the target of a package sent to CNN, fired back.

"Stop blaming others. Look in the mirror," Brennan tweeted. "Your inflammatory rhetoric, insults, lies, & encouragement of physical violence are disgraceful. Clean up your act .... try to act Presidential."

The list of bombing targets spread from New York, Delaware and Washington, D.C., to Florida and California.

The explosive devices were packed in envelopes with bubble-wrap interiors bearing six American flag stamps and the return address of Florida Rep. Debbie Wasserman Schultz, the former chairwoman of the Democratic National Committee.

The bombs seized Wednesday were about six inches long and packed with powder and broken glass, according to a law enforcement official who viewed X-ray images. The official said the devices were made from PVC pipe and covered with black tape. At the New York briefing, authorities confirmed that at least some of the packages were distributed through the U.S. mail, and cautioned that there could be additional devices in the postal system. They said investigators searching for more suspicious parcels had not found any during the previous eight hours.

David Chipman, a retired federal ATF agent and now senior policy adviser for the Giffords Center, said the details revealed telltale signs that could help guide investigators.

The tape on the pipe is "an investigator's dream," he said, recalling a case in Texas that was solved because the fibers on the tape were traced to the bomber's dog. He said bombers tend to plot methodically.

"This is someone sitting down and spending time thinking about what they're going to do to someone else. And some people like to relish that," he said.

The new packages discovered Thursday set off a new wave of alarm.

A retired New York police detective working in security in De Niro's Manhattan office called police after seeing images of a package bomb sent to CNN and recalling a similar package addressed to the actor, officials said.

The packages addressed to Biden were intercepted at Delaware mail facilities in New Castle and Wilmington, according to a law enforcement official who, like others, wasn't authorized to discuss the investigation and spoke on condition of anonymity.

Like earlier targets, both Biden and De Niro have been sharply critical of Trump. The actor dropped an expletive insult at Trump at this year's Tony Awards and also apologized to Canadians for the "idiotic behavior of my president." Biden said last week that the president may not "know what he's doing" and coddles dictators.

Trump has called Biden "Crazy Joe" and "mentally weak."

On Thursday, during a campaign trip to suburban Buffalo, Biden said: "We've got to get off this hate machine. We've got to come together."