Investigators plan to question a man who supplied parts for a gun used in the shooting at a Manhattan office building that houses the National Football League’s headquarters

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. The shooting took place at a skyscraper that is home to the headquarters of both the NFL and Blackstone,

A police officer was among the dead. The gunman carried an M4 rifle and died after shooting himself in the chest, police said.

No motive has been announced. A suicide note was found expressing grievances with the NFL and saying Tamura suffered from CTE, a source said. Follow for live updates.

FBI Deputy Director Dan Bongino said agents from the bureau’s New York field office were responding to the area to provide support.

Four people were killed and a fifth was injured in a mass shooting at a Midtown Manhattan office building on Monday. Among the victims was an officer who was a dad of two with a third on the way. Here's what we know about the victims: Officials identified the others killed in the shooting as two men and a woman,