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.

Then officials say the suspect then got into the elevator and headed to the 33rd floor, the headquarters of Rudin Management. Daughtry said "extremely dramatic and horrifying" surveillance video showed the gunman immediately opened fire as he stepped off the elevator, shooting out the glass doors.