On Monday afternoon, Sebije Nelovic, a cleaner at 345 Park Avenue in Midtown, Manhattan, began her daily sweep of the glassy high-rise building where she has worked for 27 years.

Two hours into her shift, as she was at work on the 33rd floor, came the sound of gunshots.

In a lengthy statement shared by the 32BJ Service Employees International Union on Thursday, 65-year-old Nelovic described coming face-to-face with Shane Devon Tamura, the 27-year-old gunman who authorities say entered the office tower shortly before 6:30 p.m., armed with a high-powered AR-15-style rifle, and killed four people, including an off-duty New York City police officer.

When Nelovic heard the sound of the gunshots on the 33rd floor, she said she left the office she was cleaning and turned the corner where she could see the glass door by the reception desk.

“Suddenly, the glass door was shaking. It started falling down – boom. And this guy came in the middle of the door, and pointed his gun at me,” she said in the statement. “He started shooting around me. I put my hands up and said, ‘I’m a cleaning lady. I’m a cleaning lady.'”

Then Nelovic ran, she said in the statement. She found a closet and locked herself inside.

“I started praying,” she said, as she heard the shooting continue. “He shot the door to the closet, and I was so scared.”

While hiding in the closet, Nelovic said she texted with her supervisor, but then, afraid that any noise could give away her position, she powered off her cellphone. For two to three long hours, she said she sat in silence and prayed.

When the gunfire finally ceased, Nelovic said she thought about Julia Hyman, the 27-year-old associate at Rudin Management, who she knew was scheduled to be at her desk that evening on the 33rd floor.

Later on Monday night, Nelovic returned to her Queens home, and surrounded by family, she turned on the television.

“I had to see what happened and why,” she said. “That’s how I found out about Julia.”

Police said Hyman was the last person Kamura shot and killed before taking his own life.

Investigators say they are continuing to look for a motive, but New York City Mayor Eric Adams said it appears Tamura, a former high school football player, was attempting to target the headquarters of the National Football League, located in the 345 Park Ave. building but took the wrong elevator and ended up in the 33rd-floor office of Rudin Management.

In a note found in Tamura’s pocket in the aftermath of the attack, the suspect claimed he suffered from chronic traumatic encephalopathy (CTE), a disease linked to repeated hits to the head, often seen in military veterans and athletes, including football players, hockey players and boxers, sources told ABC News. In the note, Tamura asked that his brain be studied, sources said.

It remains unknown if Tamura suffered from CTE, which can’t be diagnosed in a living person with certainty, though doctors may suspect it based on symptoms and a history of head trauma.