Dec. 7 (UPI) -- CNN's New York offices and studios were evacuated Thursday night because of a phoned-in bomb threat, forcing a network program off the air.
One hour later, the city police department issued an "all clear."
"Around 10:35pm, a bomb threat was called into the Time Warner Center & the building was evacuated," NYPD posted on Twitter. "The threat has not been substantiated at this time; we're on scene performing a comprehensive sweep-and-search of the facility."
Several fire alarm bells rang inside CNN's New York newsroom after the call was received, the company's security said.
Don Lemon's CNN Tonight, which was on a commercial break whens the alarm went off, was taken off the air and the network went to taped programming for about half hour before going live from the street.
"We were told to evacuate the building and to do it as soon as possible," Lemon said. "We grabbed what we could and got out of the building and now, we are standing outside of the building."
Police and fire department trucks blocked all vehicle and pedestrian traffic in the area.
"Due to a police investigation at Columbus Circle, West 58th Street between 8th and 9th Avenue is closed to vehicle and pedestrian traffic. Please avoid this area," NYPD tweeted.
"The building is secure and safe for everyone to return in the morning. We appreciate the swift action by the local authorities, and the patience and professionalism of all the employees who were impacted."
In October, the CNN building was evacuated after a package with an explosive device, addressed to former CIA Director John Brennan, was discovered. The device didn't detonate.
Cesar Sayoc, 56, was charged with sending more than a dozen improvised explosive devices to prominent Democratic politicians and donors around the United States.