Manhattan, July 29 -- A gunman armed with an AR-15-style rifle opened fire inside a Manhattan skyscraper on Monday evening (local time), killing four people, including an off-duty police officer, before taking his own life, according to The New York Times.

The shooting took place at 345 Park Avenue, a 44-story building in Midtown owned by Rudin Management, which houses companies such as Blackstone and the National Football League (NFL). The incident caused panic in the busy business district during rush hour.

Officials said the gunman first shot and killed an off-duty New York City police officer who was working security at the building. He then fatally shot three others, including a woman on the 33rd floor where Rudin Management's offi...