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.

Among the dead were a police officer, a security guard and two people who worked at companies in the building. An NFL employee was badly wounded but survived.

The man who stormed a Manhattan office tower with a gun, killing four people before killing himself, worked in the surveillance department of a Las Vegas casino, part of an industry built on watching for threats before they unfold.