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.

NEW YORK (AP) — A man stalked through a Manhattan office tower firing a rifle Monday, killing four people, including a New York City police officer, and wounding a fifth before taking his own life, officials said.

New York City has some of the toughest gun laws in the nation. But Monday’s mass shooting showed their limits, security experts said.