A police investigation into a report of a suspicious package in Manhattan has unearthed an apparent time capsule, the NYPD says. 

Construction crews working at a Flatiron site found an object in the shape of a World War II shell, and police were called to investigate, officials said. 

A portion of 21st Street near Fifth Avenue was shut down by police, including an NYPD bomb squad, responded. 

Office workers in the area tweeted that their buildings had been evacuated, and photos posted to social media showed heavy police presence. 

Police issued an all-clear a short time later and deemed the area safe. 

The object, it turned out, was filled with papers and may have been a time capsule, police said.