CNN's New York offices and studios remain evacuated, more than three hours after the suspicious device was delivered to the mailroom.
"The security sweep of our building continues," CNN President Jeff Zucker said in a 1 p.m. ET update to staffers.
"There was some powder found within the package that was sent, and that powder now needs to be examined to determine what it is. As a result, it will take some time until we know more about the safety of the building."
In the meantime, staffers are working from nearby hotels, restaurants and other locations.
"I want to commend all of our colleagues in New York, in particular, and elsewhere, who have helped keep us on the air as this crisis has unfolded," Zucker wrote. "I am really proud of all of you. Thank you."