Four people were killed, including an off-duty New York City police officer, when a gunman opened fire in an office tower before fatally shooting himself, officials said.

Four people have been killed, including one NYPD officer, after gunfire erupted in Midtown Manhattan Monday afternoon, officials said. Here's a look at what happened in New York Monday evening. All time stamps are based on East Coast times. Four people were shot and killed in Midtown Manhattan on Monday.

Midtown Manhattan was somber and on-edge after a mass shooting at an office tower left four people and the gunman dead, including Blackstone Inc. executive and a New York City police officer.

New York native Julia Hyman worked for the real estate company that oversees the office building where the gunman killed four people.

In the aftermath of New York’s deadliest mass shooting since 2000, authorities are investigating the motives and background of the man who opened fire in a midtown Manhattan office skyscraper, killing four people and then himself.