DELAWARE -- Two packages intercepted at a Delaware mail facility were addressed to former Vice President Joe Biden and is similar to those containing bombs.
These are the ninth such packages being investigated this week.
The first crude bomb to be discovered had been delivered Monday to the suburban New York compound of George Soros, a liberal billionaire and major contributor to Democratic causes.
The FBI said an additional package was intended for former Attorney General Eric Holder, but that one ended up at a Florida office of Democratic Rep. Debbie Wasserman Schultz, whose return address was on it.
Later Wednesday, the FBI said two additional packages addressed for Rep. Maxine Waters had been intercepted that were similar in appearance to five others.
Packages were also sent to Barack Obama and Hillary Clinton, as well as CNN's New York office.
Thursday morning, NYPD was investigating an eighth package addressed to actor Robert De Niro and sent to the address of his production company.
The bombs, each with a small battery, were about six inches long and packed with powder and broken glass, said a law enforcement official who viewed X-ray images and spoke on condition of anonymity to discuss an ongoing investigation.
The official said the devices were made from PVC pipe and covered with black tape.