MANHATTAN, N.Y. (WPIX) – Five people were shot, four fatally – including an off-duty NYPD officer – when a man carrying a long gun opened fire in a Manhattan skyscraper in Midtown Monday evening, officials said.

The officer who was 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.

“He died as he lived. A hero,” police Commissioner Jessica Tisch said at a news conference. He was married with two young boys, and his wife is pregnant with their third child, she said.

Police said the suspect, identified as Shane Tamura, of Nevada, shot and killed himself.

“We are still unraveling what took place,” said Adams. “Five innocent people were shot tonight. We lost four souls to another senseless act of gun violence, including a member of the NYPD, Officer Didarul Islam of the 47th precinct.” He was only 36 years old and a 3 and a half year veteran of the department.”

As of roughly 10:30 p.m. Monday, the fifth shooting victim was in critical condition at an area hospital, Adams said.

Cameras record gunman ‘immediately opening fire’

The shooting took place in the lobby of Blackstone, the building that houses some of the country’s top financial firms and the National Football League.

“At around 6:28 p.m., the 911 call center started receiving reports of an active shooter inside 345 Park Avenue,” said NYPD Commissioner Jennifer Tisch.

Tisch said that surveillance footage shows the suspect stepping out of a black BMW parked in front of the building, an M4 rifle in his right hand.

“The building security camera footage shows the shooter entering the lobby, turning right, and immediately opening fire at an NYPD officer,” Tisch said. “He then shoots a woman who took cover behind a pillar. He makes his way to the elevator bank, where he shoots a security guard who was taking cover behind the security desk. One additional male was shot in the lobby, per his own statement.”

Tisch said the video also shows him allowing a female to walk out of the elevator unharmed before he steps in.

“He goes up to the 33rd floor and begins to walk the floor, firing rounds as he travels. One person was struck and killed on that floor,” Tisch added. “He proceeds down the hallway and shoots himself in the chest.”

Tisch said police searched the vehicle and found a rifle case with rounds, a revolver, and ammunition. “The vehicle traveled cross country through Colorado on July 26, Nebraska and Iowa on July 27, and Columbus, New Jersey, at 4:24 p.m. today.”

Mourning the loss of Officer Islam

“He embodies what this city is all about,” Mayor Adams said of Officer Islam.

Adams added that Islam was an immigrant from Bangladesh who loved the city, calling him a “true, blue New Yorker.”

“Everyone we spoke with stated he was a person of faith and a person that believed in God,” Adams said.

The other victims, two males and a female, were not immediately identified.

“Gun violence has scarred so many neighbors and ripped apart too many families across this entire country,” Adams said. “We will continue to fight to do all we can to protect our city, but tonight, we mourn for those who were killed, and we pray for the families.”

Police work to uncover a motive

NYPD officials said Monday night they believe the gunman acted alone, but any motive remained unclear. Tisch added that law enforcement partners in Las Vegas told the NYPD that Tamura has a documented mental health history.

The building was evacuated around 7 p.m.; footage from the scene showed people dressed in business attire walking out of the building with their arms raised above their heads.

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.

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.

The city’s emergency management alert system warned of traffic delays, road closures and disruptions to public transportation in the area.

Through late July, New York City is on pace to have its fewest murders and fewest people hurt by gunfire than any year in recent decades.

The Associated Press contributed to this report.