A 50-story midtown Manhattan office tower received an anonymous bomb threat Monday morning, prompting thousands of tenants to leave the building at 1345 Avenue of the Americas.

Around 10:45 a.m., an announcement over the building’s public address system specified that the 20th floor of the building was named as a target. The announcement also stated that concerned tenants should take the stairs and leave the building. An acquistions firm called Braodview occupies the entire 20th floor of the building, according to CoStar.

"A lot of people were filing out of the building. It was very crowded in the stairwells but also very orderly," says one tenant who works above the 20th floor of the building. Fortunately, the threat turned out to be a false alarm. Most people returned to their offices by 2 p.m., according to the tenant.

The 1.7 million sq. ft. 1345 Avenue of the Americas is located on Sixth Avenue between 54th and 55th street. The building’s tenant roster includes hedge funds, anchor tenant Alliance Capital and public relations firm Rubenstein Associates. The building is owned and managed by Fisher Brothers, a closely held owner/developer based in Manhattan.