The FBI is investigating after an NBC worker tested positive for anthrax.
The news company says the female worker is in no danger and should recover fully.
NBC says the anthrax is not the same strain that killed a Florida man.
The woman, who has not been identified, has tested positive for a cutaneous (skin) anthrax infection.
The network says it had received some suspicious mail and immediately contacted the FBI, Centre for Disease Control and the New York Department of Health.
"The mail was tested by these organisations, and the employee was treated by several physicians. All these tests came back negative," said the NBC statement.
"However, this morning, a later test on the employee came back positive for traces of cutaneous anthrax."
New York police are also investigating a suspicious package removed from the headquarters of the New York Timesin midtown Manhattan, but a company spokeswoman said its employees were safe.
"We are investigating a suspicious package," a spokeswoman said. "The package was removed. The police are here to make sure that everyone is safe." She declined to comment on what the suspicious package was.
PA