4 dead, including off-duty police officer, in Midtown Manhattan shooting: Officials

A 27-year-old man wearing body armor and carrying a high-powered M4 rifle shot and killed four people, including an off-duty police officer working security in a Midtown Manhattan office building, officials said during a press conference Monday evening.

A fifth victim was left critically injured in the shooting, officials said.

The incident occurred just before 6:30 p.m. in a building located at 345 Park Ave. and 52nd Street, which contains the headquarters for the investment company Blackstone and the National Football League, sources told ABC News.

It is unclear if those companies, or any company in the building, were tied to the shooting.

After apparently barricading himself on the 33rd floor, the suspect, who was identified as Las Vegas resident Shane Devon Tamura, was found dead from what is believed to be a self-inflicted gunshot wound, according to New York Police Department Commissioner Jessica Tisch.

During a press conference on Monday evening, Tisch said preliminary information suggests the suspect traveled cross-country by car from Las Vegas before arriving in New York City.

Tamura had a license to carry a concealed weapon in the state of Nevada. "We believe this to be a lone shooter," Tisch said.

The man emerged from a double-parked BMW in front of the office building and entered the lobby alone and immediately opened fire on an NYPD officer and sprayed the lobby with bullets, Tisch said.

He made his way to the elevator bank, where he shot a security guard, Tisch said. He then went up to the 33rd floor, where he shot another person before shooting himself in the chest, she added.

Officers searched the suspect's vehicle after the shooting, where they found a rifle case with rounds, a loaded revolver, ammunition and magazines, a backpack "and medication prescribed to Mr. Tamura,” Tisch said. The motive is currently under investigation, FBI Deputy Director Dan Bongino said earlier on Monday.

A witness inside the Midtown office building at the time of the shooting detailed to ABC News what it was like at the scene as colleagues hid in lockdown, unsure of what was unfolding.

"We heard multiple shots go off in quick succession from the first floor, and a lot of us just rushed into the room," Jessica Chen said, adding that she was on the second floor of the building watching a presentation with about 150 other people when the shooting started.

"Some went out in the back door, out onto the street. Other people, including me, we ran into the conference room and then eventually barricaded the tables across the doors and just stayed still," Chen said.

"I texted my parents, 'I love them,'" Chen said. "Nothing can describe that feeling."

Chen went on to say that she recalled doing active shooter drills in school and said she often wondered what she would do in this kind of scenario. "It's unfortunate that all Americans could think this through," Chen said.

FBI New York Field Office management personnel and agents responded "to provide support at the active crime scene in Manhattan," Bongino said on X.

New York Gov. Kathy Hochul said she has been briefed on the situation.

KPMG, an accounting firm that also has offices in the building, released a statement after the shooting, saying, "Our hearts go out to the victims of this horrific act and their families."

"We are incredibly grateful for the bravery of building security and law enforcement," the company said.