Surveillance footage showed a young man approaching the building with a large rifle.
At least two people are dead following a shooting at 345 Park Avenue in Manhattan on Monday.
The Fire Department of New York said it received a call about a shooting at the Midtown building around 6:30 p.m. The office building houses the offices of the National Football League and the Blackstone Group.
New York Post reporter Dorian Gieger was on the scene and shared a statement from an unnamed witness.
