NEW YORK (NEXSTAR) — A tragic shooting occurred in a Manhattan office building Monday, where a man with a rifle took the lives of four individuals, including a New York City police officer, and injured another person before ending his own life, as reported by officials.

The incident happened in a skyscraper that houses the headquarters for both the NFL and Blackstone, one of the leading investment firms globally, along with several other businesses.

The shooter, identified by authorities as Shane Tamura from Las Vegas, had a known history of mental health issues, according to Police Commissioner Jessica Tisch, although the reason behind his actions remains unclear.

“We are working to understand why he targeted this particular location,” Tisch said.

The rampage happened at the end of the workday in the same part of Manhattan where the chief executive of UnitedHealthcare was gunned down outside a hotel late last year.

Building houses NFL HQ, KPMG, Blackstone and Rudin Management

Surveillance video showed the man exiting a double-parked BMW just before 6:30 p.m. carrying an M4 rifle, then marching across a public plaza into the building. Then, he started firing, Tisch said, killing a police officer working a corporate security detail and then hitting a woman who tried to take cover as he sprayed the lobby with gunfire.

The man then made his way to the elevator bank and shot a guard at a security desk and shot another man in the lobby, the commissioner said.

The man took the elevator to the 33rd floor offices of the company that owned the building, Rudin Management, and shot and killed one person on that floor. The man then shot himself, the commissioner said. The building, 345 Park Avenue, also holds offices of the financial services firm KPMG.

The NFL, which has offices in the building, confirmed that one of its employees was seriously injured in the shooting. Commissioner Roger Goodell said the injured NFL employee was undergoing treatment at a hospital.

He also urged New York NFL employees to work from home or take the day off as the investigation into the mass shooting continues on Tuesday.

The officer killed was an immigrant

The officer killed was Didarul Islam, 36, an immigrant from Bangladesh who had served as a police officer in New York City for 3 1/2 years, Tisch said at a news conference.

“He was doing the job that we asked him to do. He put himself in harm’s way. He made the ultimate sacrifice,” Tisch said. “He died as he lived. A hero.”

One man was seriously wounded and remains in critical condition, Mayor Eric Adams said. Four others got minor injuries attempting to flee.

Adams said officials are still “unraveling” what took place.

Officers found a rifle case, a revolver, magazines and ammunition in Tamura’s car, Tisch said. They also found medication that belonged to Tamura, she said.

She said an initial investigation shows his vehicle traveled across the country, passing through Colorado on July 26, then Nebraska and Iowa on July 27. The car was in Columbia, New Jersey, as recently as 4:24 p.m. Monday. He drove into New York City shortly thereafter, she said.

Rudin is one of the largest privately owned real estate companies in New York City. The company dates back to 1925 and is still managed by members of the Rudin family.

Tisch said there were no indications so far that Tamura had prior connections to the real estate industry or to the city.

No one answered the door at the address listed for Tamura in Las Vegas.

Islam, the officer who was killed, leaves behind two young boys, and his wife is pregnant with their third child, Tisch said.

Witnesses heard ‘rapid fire’

Local TV footage showed lines of people evacuating the office building with their hands above their heads in the hours after the killings.

Nekeisha Lewis was eating dinner with friends on the plaza when she heard gunfire.

“It felt like it was a quick two shots and then it was rapid fire,” she told The Associated Press.

Windows shattered and a man ran from the building saying, “Help, help. I’m shot.” Lewis said.

Jessica Chen told ABC News she was watching a presentation with dozens of other people on the second floor when she “heard multiple shots go off in quick succession from the first floor.”

She and others ran into a conference room and barricaded tables against the door.

“We were honestly really, really scared,” she said, adding that she texted her parents to tell them that she loves them.

Some finance workers at an office building down the block were picking up dinner at a corner eatery when they heard a loud noise and saw people running.

“It was like a crowd panic,” said Anna Smith, who joined the workers pouring back into the finance office building. They remained there for about two hours before being told they could leave.

Tisch says she believes two officers were working in different parts of the building as part of a program where companies can hire NYPD officers to provide security.

The building where the shooting happened is in a busy area of midtown, located a short walk north from Grand Central Terminal and about a block east of St. Patrick’s Cathedral.

Through late July, New York City is on pace this year to possibly have its fewest homicides and fewest people hurt by gunfire in decades. But the city’s corporate community has been on edge since last December, when UnitedHealthcare CEO Brian Thompson was killed outside a hotel hosting a conference.

The man charged in that killing, Luigi Mangione, is awaiting trial. Prosecutors accuse him of killing Thompson because he was angry at perceived corporate greed, particularly in the health insurance business. He has pleaded not guilty.

The Associated Press contributed to this report.