The horrific mass shooting at a Midtown office building on Monday was the deadliest gun attack in the Big Apple in 25 years. Shane Tamura gunned down four innocent people — including an NYPD cop and a business executive — before turning the gun on himself late Monday.

A New York City office building where a gunman killed four people then himself has reopened a week after the deadly shootings. On Monday, workers trickled back into 345 Park Avenue in Midtown Manhattan, a skyscraper home to high-profile tenants including the NFL and asset management firm Blackstone.