Shane Tamura sprayed nearly 50 rounds during Midtown Massacre

Maniac Shane Tamura sprayed nearly 50 bullets during his Midtown massacre — as he shot dead four people, including an NYPD officer, according to police and sources.

The deranged gunman sprayed most of the bullets across Rudin Management’s 33rd-story offices at 345 Park Ave. — which he entered after mistakenly getting off on the wrong floor during his search for the NFL headquarters, authorities said.

Cops recovered 24 discharged shell casings and 15 bullet fragments on that floor, which is where Tamura gunned down 27-year-old Julia Hyman, an associate at the real estate company, before turning the weapon on himself, according to cops’ initial investigation.

Another 23 casings and 13 bullet fragments were found in the lobby and the ground floor of the skyscraper where Tamura, 27, unleashed his Monday rampage, authorities said.

Police found more than 800 unspent 357 Magnum Rounds sitting in the black BMW that Tamura was seen exiting while brazenly carrying an M4 rifle just before storming into the Park Avenue building, according to cops.

The crazed gunman immediately delivered a fatal shot at NYPD hero Didarul Islam, who was working an extra shift on a security detail, upon entering around 6:30 p.m., then killing 43-year-old Blackstone executive Wesley LePatner as she hid behind a lobby column and building security guard and father Aland Etienne. who was at his desk.

Tamura then took the elevator — shockingly allowing one woman to exit the lift unharmed — and dialed up the violence after apparently realizing his plan to target the NFL fell apart, authorities said.

The madman left behind a suicide note revealing he targeted the sports organization because he believed he was suffering from chronic traumatic encephalopathy (CTE) — despite not playing the sport past high school.

Tamura railed against the NFL in the three-page missive, which referred to Terry Long, the former Pittsburgh Steelers player who was diagnosed with CTE after downing antifreeze to kill himself 20 years ago.

“Please study brain for CTE. I’m sorry. The league knowingly concealed the dangers to our brains to maximize profits,” the note read.

“They failed us.”

The gunman had a history of mental health issues, and investigators found prescription medication for depression and epilepsy in his Las Vegas home, authorities said.

Also found in the home was a note in which Tamura revealed he felt like a “complete disappointment” to his parents, including his retired cop father, sources said.