The head of a major American health insurance company was shot dead on a sidewalk in New York City on Wednesday in what appeared to be a "brazen targeted attack," according to police.

Brian Thompson, CEO of UnitedHealthcare, was killed as he walked into the Hilton hotel in midtown Manhattan just before 6:45 a.m. ET. Police said the attacker had been waiting for Thompson, who had arrived early for the company's annual investors conference.

"At this time, every indication is this was a premeditated, preplanned, targeted attack," New York City Police Commissioner Jessica Tisch said at a press conference Wednesday.

The police department's chief of detectives Joseph Kenny said security footage showed the shooter getting to the hotel about five minutes before Thompson, who had been staying in another hotel across the street. Standing along the building's edge, the suspect let "numerous" other people pass by unharmed before opening fire on the businessman.

WATCH | Police commissioner's full remarks: 

Health insurance CEO shot dead in 'brazen targeted attack,' police say

New York City police Commissioner Jessica Tisch said Brian Thompson, 50, was shot dead in what appears to be 'a premeditated, preplanned, targeted attack' in Manhattan.

The gun malfunctioned, but video showed the shooter clearing the jam before continuing. The video does not have sound, Kenny said, so officers didn't yet know whether the shooter said anything to Thompson.

Thompson, 50, had been in the city from Minnesota since Monday. Kenny said he did not appear to have a security detail and did not seem to realize he was in danger.

UnitedHealthcare is the insurance arm of the health-care giant UnitedHealth Group Inc. The Minnesota-based company was scheduled to have its annual meeting with investors in New York City to update Wall Street on the company's direction and expectations for the coming year, according to a company media advisory.

An announcement was made to attendees Wednesday morning that the conference was ending early.

"Brian was 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," read a company statement.

"Our hearts go out to Brian's family and all who were close to him."

The Hilton is in a bustling part of Manhattan, a short walk from tourist sites such as the Museum of Modern Art and Rockefeller Center and often dense with tourists and office workers on weekday mornings. The popular Rockefeller Center Christmas tree lighting is set to take place Wednesday evening. 

Part of the block where the shooting took place was cordoned off with police tape, with a large contingent of police officers at the scene. 

Thompson had served as CEO for more than three years and had been with the company since 2004. Police said they are still working to determine a motive. Officers are also working with Citi Bike to track the bicycle the shooter used.

Minnesota Gov. Tim Walz tweeted that the state is "sending our prayers to Brian's family and the UnitedHealthcare team."

"This is horrifying news and a terrible loss for the business and health-care community in Minnesota," the Democrat wrote. 

UnitedHealthcare is the largest provider of Medicare Advantage plans in the U.S. and manages health insurance coverage for employers as well Medicaid programs funded by the state and federal governments.