A federal official said federal investigators were trying to track down a suspicious package they believe was directed at former Vice President Joe Biden.
Former President Barack Obama was among the targets of at least five explosive-laden parcels sent to senior Democratic Party and CNN officials in what officials in New York called an act of terrorism.
The FBI also found two suspicious packages sent to California Congressman Maxine Waters, similar to a package intercepted before reaching former US President Barack Obama and other senior members of the Democratic Party.
By sending the packages to Waters, a veteran Democrat from Los Angeles and one of President Donald Trump's most vocal critics, the total number of suspicious packages containing explosives is being investigated and eight are being investigated.
On the other hand, US President Donald Trump called on the media to stop its "continuing hostility" and "deceptive attacks" in commenting on the parcels sent to Obama.
In a speech to supporters at an election rally in the city of Mozzini, Wisconsin, the president began with thoughtful comments that public figures have a duty to tone down their rhetoric.
"No one should compare the disdain of political opponents to the evil historical figures, which is what happened, and what always happens," he said.
"The media also have a responsibility to put in place civil controls, stop the ongoing hostility and persistent negative reports, which are often misleading attacks," he said.
"They must stop," he said.
