The gunman in the deadly shooting at a New York City office tower had a background in casino surveillance and once held a private security guard license.

New York City investigators believe a co-worker of the Las Vegas man who killed four, including a police officer, provided a component of the deadly weapon, the 8 News Now Investigators have learned.

Shane Tamura, the man accused of killing four people in New York City, bought the weapon used in the attack from his boss at a Las Vegas casino. Meanwhile, FOX 5 New York has obtained exclusive images from inside the car Tamura drover from Vegas to New York.

The killing of four people including a police officer in a Midtown Manhattan office building rattled a city where mass attacks are rare and violent crime has declined.

Officials say a man carrying a rifle killed four people at a New York City office tower. The shooting took place Monday afternoon at a midtown Manhattan office building that houses finance companies and the NFL headquarters.