It was supposed to be joke on General David Petraeus, but the New York City Police Department wasn't laughing.
Police say a friend mailed a fake grenade to General Petraeus' office in the Solow Building on 58th Street.
His secretary opened the box around noon Tuesday and saw what she thought was a real grenade.
Investigators describe it as a "novelty item."
Police evacuated the office and shut down 58th Street between Fifth and Sixth Avenues.
They took the package to the building's courtyard to get a closer look.
"Just a lot of police officers, a lot of people that worked in the buildings, "The higher-ups were outside, talking to each other. It didn't really look like it was too big of a deal, but there were a lot of cops so, you know, it was something to be worried about."
It's unclear if Petraeus was in the building at the time.
His office hasn't replied to calls for comment.