Police have lined up four rows deep to pay respects to a fellow officer who was among the victims of a gunman's rampage at a Manhattan office tower.

Follow along for live updates on the New York City shooting, where police investigate motive after five people, including the gunman, were killed in the Monday shooting.

A New York City police officer and three other people were killed in a shooting in Midtown Manhattan on Monday evening, police confirmed at a late-night news conference.