A police officer and three other people were shot and killed, and one other injured, by a crazed gunman who stormed a swanky Midtown skyscraper early Monday evening — before turning the gun on himself,

The guard had been fatally shot as he crouched behind a desk to take cover as the gunman sprayed the building’s lobby with bullets, police said.

NYC gunman Shane Tamura is seen on video talking about his high school football career in California after a game in September 2015.

Shane Tamura, the Park Avenue gunman who killed an NYPD officer and three others before taking his own life, left behind a suicide note saying he suffered from CTE, a brain injury often linked to playing football,