A man carrying a rifle killed four people at a New York City office tower Monday, including an off-duty New York City police officer, and wounded a fifth before taking his own life

Four people, including an off-duty New York City police officer, were killed Monday when a gunman carrying a rifle opened fire inside a Midtown Manhattan office tower, authorities said.

Police executed a search warrant at the Las Vegas apartment of Shane Tamura, where the items obtained included a goodbye note and a bipod for a rifle.