NEW YORK - A law enforcement official says a package addressed to former Vice President Joe Biden appears similar to packages containing bombs sent to prominent Democrats and has been intercepted at a Delaware mail facility.

The official wasn't authorized to discuss an ongoing investigation publicly and spoke to The Associated Press on Thursday on the condition of anonymity.

The FBI confirms there is law enforcement activity at the U.S. mail facility in New Castle, Delaware. It says federal agents and New Castle County Police are responding to the facility.

Earlier Thursday, authorities said a suspicious package was sent to actor Robert De Niro Thursday morning in New York.

Sources say the package is similar to ones that were sent Wednesday to several high-profile politicians and CNN, which contained "potentially destructive" devices.

The bomb squad responded, examined the device under an X-ray and removed it. Sources told CBS News that the package appears to be from the same sender who targeted former U.S. presidents and other politicians on Wednesday.

The Secret Service intercepted two packages that were addressed to former President Obama's home in Washington and Bill and Hillary Clinton's residence in Westchester County, New York.

Another package was addressed to former CIA Director John Brennan at the New York City offices of CNN, prompting CNN's bureau and the Time Warner Center to evacuate.

Crude but functional low-ordnance explosive devices found in at least two of the packages consisted of a pipe, wires and black powder, a law enforcement official told CBS News senior investigative producer Pat Milton.