• Brian Thompson, the CEO of UnitedHealth Group's insurance unit, was fatally shot outside the Hilton hotel in midtown Manhattan on Wednesday morning, in what appears to be "a brazen, targeted attack," the New York Police Department said.
• The gunman is described as using a firearm with a silencer, a person familiar with the matter said.
• Thompson led UnitedHealthcare, the largest private health insurer in the U.S.

Brian Thompson, the CEO of UnitedHealth Group's insurance unit, was fatally shot outside the Hilton hotel in midtown Manhattan on Wednesday morning in what appears to be "a brazen, targeted attack," the New York Police Department said.

"I want to be clear at this time, every indication is that this was a premeditated, preplanned, targeted attack," Police Commissioner Jessica Tisch said during a news conference Wednesday following the shooting.

"This does not appear to be a random act of violence," she said, adding that the department is carrying out a full investigation.

The gunman was still at large more than 24 hours later.

Thompson, 50, led UnitedHealthcare, the largest private health insurer in the U.S. He was on the way to UnitedHealth Group's investor day set for Wednesday at 8 a.m. ET at the Hilton, the NYPD said. The company canceled that event after the shooting.

Patrol officers responded to a 911 call at 6:46 a.m. ET about a person shot in front of the Hilton hotel at 1335 Avenue of the Americas, NYPD Chief of Detectives Joseph Kenny said during the news conference. Officers arrived at 6:48 a.m. ET to find Thompson on the sidewalk with gunshot wounds to his back and leg, he added. 

Emergency medical services brought Thompson to Roosevelt Hospital where he was pronounced dead at 7:12 a.m. ET, according to Kenny.

Thompson had been staying at The Luxury Collection Hotel Manhattan Midtown, a Marriott-affiliated property located on 54th Street, according to NBC News.

The gunman showed up at the location on foot, roughly five minutes before Thompson arrived outside the Hilton, Kenny said. Several people passed him as he waited for Thompson, he added.

Prior to the shooting, the gunman stopped by a Starbucks in midtown and bought several items he later discarded, including a water bottle and two protein bars, a senior NYC law enforcement official briefed on the investigation told NBC News.

As Thompson walked alone toward the Hilton, the shooter stepped onto the sidewalk from behind a car and approached Thompson from behind, firing several rounds that struck him at least once in the back and at least once in the right calf, according to Kenny and security video obtained by NBC News. After initial shots, the gun appeared to malfunction before the assailant fired again.

Following the shooting, the gunman fled on foot into an alleyway between 54th and 55th streets, according to Kenny. He said the shooter then walked west on Avenue of the Americas, where he got onto an e-bike and rode toward Central Park.

Tisch said the assailant was last seen in Central Park on Center Drive early this morning. Kenny said the gunman wore a black face mask, black and white sneakers, and a "very distinctive" gray backpack. The video of the shooting showed the shooter wearing a hooded jacket.

The NYPD recovered three live 9 mm rounds and three discharged 9 mm shell casings at the scene, Kenny said. He added that they recovered a cellphone.

No arrests have been made. The NYPD has increased the reward in the case to $10,000, Tisch noted.

The gunman was described as using a firearm with a silencer, a person familiar with the matter told CNBC.

Kenny said the NYPD is unable to determine yet whether the shooter used a silencer. The department will investigate that further, he said.

A hot dog vendor near the Hilton who was present at 6:30 a.m. ET said he did not hear any gunshots but noticed a sudden swarm of police. A Hilton doorman who began his shift at 7 a.m. ET said everything appeared to be "pretty normal" at the hotel. Both people asked not to be named.

Thompson is survived by his wife, Paulette Thompson, and their two children.

Thompson's wife told NBC News that he had been receiving threats. She said the NYPD told her it was a planned attack.

"Yes, there had been some threats basically I don't know, a lack of coverage? I don't know details," she told NBC News. "I just know that he said there were some people that had been threatening him."

She told NBC News that Thompson did not alter any of his travel habits despite the threats.

"I can't really give a thoughtful response right now," Paulette Thompson told NBC News. "I just found this out and I'm trying to console my children. "

UnitedHealth Group is the biggest health-care conglomerate in the United States based on revenue and its roughly $563 billion market cap. UnitedHealthcare posted more than $281 billion in revenue last year, making up more than two-thirds of UnitedHealth Group's annual revenue for 2023.

Shares of UnitedHealth Group rose more than 1% on Wednesday.

In a statement Wednesday, UnitedHealth Group said it was "deeply saddened and shocked at the passing" of Thompson. The company called him a "highly respected colleague and friend to all who worked with him."

"We are working closely with the New York Police Department and ask for your patience and understanding during this difficult time," UnitedHealth Group said. "Our hearts go out to Brian's family and all who were close to him."

Earlier Wednesday, the company canceled its investor event when it acknowledged a "medical situation" with an employee.

"I'm afraid that we – some of you may know we're dealing with very serious medical situation with one of our team members," Chief Executive Officer Andrew Witty said during the investor day, according to a transcript. "And as a result, I'm afraid we're going to have to bring to a close the event today, which I'm sure you'll understand."

Thompson had worked for United Health for just over 20 years, joining the company in April 2004 after spending nearly seven years at PwC, according to his LinkedIn page. He stepped in as CEO of UnitedHealthcare in April 2021 after serving as the top executive of the insurance unit's government programs.

Thompson was a resident of Maple Grove, Minnesota, a suburb of Minneapolis, and graduated valedictorian from the University of Iowa.

He had been facing insider trading allegations.

In May, a firefighters' pension fund in Hollywood, Florida, sued United HealthGroup, Thompson, Witty and Executive Chairman Stephen Hemsley. The suit accused the executives of selling a combined $120 million in company shares before a U.S. Department of Justice antitrust investigation was disclosed publicly. 

The DOJ's probe was related to UnitedHealth Group's 2021 acquisition of Change Healthcare, which processes medical claims. 

The lawsuit claimed Thompson knew about the investigation as early as October 2023 and sold shares worth $15.1 million on Feb. 16, less than two weeks before news of the probe went public, according to the complaint.

Gov. Kathy Hochul of New York said in a statement Wednesday she was briefed on the shooting and directed the state police to provide the NYPD with any necessary help with the investigation.

"Our hearts are with the family and loved ones of Mr. Thompson and we are committed to ensuring the perpetrator is brought to justice," she said.

Gov. Tim Walz of Minnesota called the killing "horrifying news and a terrible loss for the business and health care community" in a post Wednesday on X.

UnitedHealth Group is still grappling with the fallout from a ransomware attack in February targeting its company, Change Healthcare, which processes medical claims. The attack compromised the protected health information of at least 100 million people.

— CNBC's Ester Bloom and NBC News' David K. Li contributed to this report.