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

The funeral will be held Thursday for the police officer who was one of four people killed in Monday's mass shooting at a Midtown Manhattan office building.

A gunman opened fire inside a Midtown Manhattan skyscraper on Monday, killing four people, including an off-duty NYPD officer, according to authorities. A video showed terrified people running from the office building at 345 Park Ave.