The NYPD bomb squad transported a suspicious package mailed to actor Robert De Niro in Manhattan Thursday into their training facility at Rodman's Neck.

It says the bomb was found at the Greenwich hotel.

Gov. Andrew Cuomo announced increased security to key locations such as mass transit sites, bridges and tunnels across the New York City as more mailed explosives continue to be found.

Officials say two more suspicious packages were found addressed to former Vice President Joe Biden. Police and the FBI intercepted the packages at two Delaware post offices – one in New Castle and the other in Wilmington.

"I believe there is someone who by definition is a serial bomber, yes, and a terrorist, person or people, foreign or domestic," says New York City Mayor Bill de Blasio. "We don't know yet, and we certainly don't know if they're here or elsewhere in the country."

The new acts of terror comes after seven bombs were detected and intercepted over the past three days, mailed to prominent democratic leaders and political figures.

An explosive was sent to the home of democratic billionaire George Soros in Westchester Monday. A bomb was then sent to the Clinton home in Chappaqua, but was intercepted by Secret Service Tuesday.

Police say a package was sent to the Obama home in Washington Wednesday. Officials say a "crude pipe bomb" was discovered inside the Time Warner Building at Columbus Circle that houses CNN, which forced an evacuation.

A package addressed to former Attorney General Eric Holder was intercepted, along with a package addressed to Congresswoman Maxine Waters in Maryland.

Officials say another suspicious package was found in Los Angeles.

President Donald Trump has condemned the acts of political violence.