The gunman who killed four people at an office building in New York City on Monday evening left his home in Las Vegas, Nevada late last week.

Four people were killed and a fifth was injured in a mass shooting at a Midtown Manhattan office building on Monday.The injured victim was an employee at the NFL, according to NFL Commissioner Roger Goodell.

Officer Didarul Islam, 36, who was guarding the building on a paid security job when he was killed, had served as a police officer in New York City for over three years. He was an immigrant from Bangladesh and was working a department-approved building security job when he was shot.