The CNN package contained an explosive device and was addressed to commentator and former CIA Director John Brennan, the network reported, citing city and local law enforcement officials. Brennan has sparred with US President Donald Trump, who revoked his security clearance in August, accusing him of "erratic conduct and behaviour."
"We are working with authorities to determine the severity of the situation," Zucker said. "The NYPD is on scene, and we working closely with them to take every precaution. We are also checking all bureaus around the world, out of a complete abundance of caution."
As the device was removed from the building, the New York Police Department advised residents in the area to shelter in place.
The Secret Service said it intercepted potential explosive devices addressed to former President Obama and presidential candidate Clinton. It opened a criminal investigation into the incidents.
One device was addressed to the Clinton home in Chappaqua, a suburb about 65km north of New York City. The other was addressed to Obama in Washington.
The incidents followed an earlier discovery when police "proactively detonated" a pipe bomb found at a suburban New York residence owned by Soros, a billionaire philanthropist and Democratic donor.
A CNN producer tweeted that the device sent to the Time Warner Centre, where the cable network is located, was constructed with pipe and wires, citing a law enforcement source.
"We expect more information very soon, and we ask that you remain calm and patient," CNN's Zucker said.
- Bloomberg