The crazed gunman behind the fatal rampage in a Midtown skyscraper chased and opened fire on a helpless maid who miraculously escaped unscathed, the NYPD’s chief of detectives revealed Wednesday — as he described the massacre as the worst crime scene he’s seen in 30 years.

The unidentified cleaner encountered the heavily armed Shane Tamura as he stormed the mostly deserted 33rd floor of the Park Avenue office tower soon after spraying the lobby with bullets on Monday night.

“When he gets to the top floor, he sees a maid who has been there for years, beloved, just cleaning up and doing her job when everyone leaves,” John Chell, the chief of detectives, told Fox News’ “Fox & Friends.”

6 Gunman Shane Tamura seen walking with a rifle in his hand before opening fire at 345 Park Avenue on Monday, July 28, 2025. Obtained by NY Post

6 Workers barricade the doors at 345 Park Avenue after a gunman opened fire in the building.

“He’s firing AR-15 rounds at her. The sheer terror. Thank God she got away — he made a right and she made a left.”

6 NYPD Crime Scene Unit investigator inspects a bullet hole at the scene of a deadly mass shooting in Midtown. REUTERS

Moments later, he gunned down his last victim: Rudin Management employee, Julia Hyman, who worked on the floor.

“The crime scene was horrible. Thank God this didn’t happen a half hour earlier. There were minimal people,” Chell said.

“The crime scene, the video, in three decades of doing this was just horrible,” he added.

6 NYPD officers comfort one another after the body of fallen Officer Didarul Islam was transferred to a funeral home. James Keivom

The psycho’s rampage only ended when he turned the gun on himself, authorities said.

Describing the entire ordeal as “mayhem,” the NYPD chief admitted it was among the worst scenes he has encountered on the force.

“We have casualties in the lobby. One of our own, Officer Islam. We got a mom executive, then we have a security guard. We have an NFL employee who was shot trying to call his friends up at the NFL,” he said.

6 Members of the NYPD salute and pay their respects to fallen Officer Didarul Islam. James Keivom

“We had a car out front that was the perpetrator’s car that we thought might have explosives in there.”

He said the scores of terrified workers trying to flee the building added to the chaos.

“This is not normal,” Chell said, adding he had “cops trying to negotiate calls coming in from people trapped.”

“It was mayhem. An active shooter is not a normal event. After we had to deal with the lobby … we had to go up to the 33rd floor.”

Cops later found the gunman’s body there, as well as his fourth victim.

The mentally ill shooter was found carrying a suicide note that revealed he’d targeted the NFL’s headquarters — because he believed himself to suffer a football-related brain injury.

6 The victims of the shooting: Top row from left to right: Wesley LePatner and Aland Etienne. Bottom row from left to right: Julia Hyman and Didarul Islam. Blackstone; Facebook; Obtained; Linkedin

He only ended up on the 33rd floor after mistakenly going up the wrong elevator banks in search of the NFL’s offices, according to authorities.

The other victims killed included NYPD Officer Didarul Islam, Blackstone exec Wesley LePatner and security guard Aland Etienne.

Meanwhile, detectives were still working to unravel more details about the 27-year-old’s background and motivations.

How the shooting unfolded Reports of the shooting at 345 Park Ave. start coming in around 6:28 p.m.

Shane Tamura, 27, is seen getting out of a black BMW between 51st and 52nd streets with an M4 rifle.

He enters the lobby and turns right, where he shoots police officer Didarul Islam, 36, dead.

Tamura guns down a woman cowering behind a pillar in the lobby, sprays more bullets and walks toward the elevator bank — where he shoots dead a security guard crouching at his desk.

One more man reports being shot and injured in the lobby. He was in critical but stable condition.

The gunman allows a woman to walk out of the elevators unharmed before heading up to the 33rd floor, where building owner Rudin Properties’ offices are located, “and begins to walk the floor, firing as he traveled.”

One woman is shot and killed on that floor before Tamura shoots himself in the chest.

It’s unclear how long the mayhem lasted. Police Commissioner Jessica Tisch posted on X at 7:52 p.m.: “The scene has been contained and the lone shooter has been neutralized.”

Tamura, who played high school football in California a decade ago but never played in the NFL, had a history of mental illness, police said.

It’s unclear, though, whether he showed symptoms of CTE, which can be diagnosed only by examining a brain after death.