The chief executive of UnitedHealthcare, one the nation's largest insurers, was killed Wednesday in midtown Manhattan in what police described as a targeted attack by a shooter outside a hotel where the company was holding a conference.

The shooter fled on foot into an alleyway and was last seen on an e-bike heading into Central Park. New York City police said the attack on Brian Thompson was planned, but the motive was not yet clear.

Here's what to know:

Police said Thompson was heading to the company's annual investor conference at the New York Hilton Midtown around 6:45 a.m. when a person walked up behind him and shot him multiple times.

Thompson was alone at the time and did not have a security detail, police said.

Officers found Thompson on the ground outside the hotel with gunshot wounds to his back and right calf, according to Joseph Kenny, the police department's chief of detectives. He was pronounced dead at a nearby hospital at 7:12 a.m.

Kenny said the shooter appeared to be a man who was wearing black face mask, black and white sneakers and a "very distinctive" gray backpack.

He arrived outside the hotel about five minutes before Thompson got there, waiting near the building and ignoring others before he approached Thompson from behind.

He began to fire at Thompson, hitting him in the back. The gun then malfunctioned, but he was able to quickly fix the issue and continue firing, Kenny said.

"From watching the video, it does seem that he's proficient in the use of firearms as he was able to clear the malfunctions pretty quickly," Kenny said.

The shooter ran into an alleyway near the hotel and later got onto a e-bike that he took into Central Park.

Kenny said police found a cellphone in the alleyway, but it was unclear if it belonged to the shooter.

Thompson was the chief executive of UnitedHealthcare, the insurance wing of parent company UnitedHealth Group Inc.

He had worked at the Minnetonka, Minnesota-based company for two decades and led its insurance division since 2021. He was one of the company's highest-paid executives, with a $10.2 million annual compensation package.

Thompson kept a low profile, with UnitedHealth Group Inc.'s CEO Andrew Witty taking on a more public-facing role that included testifying before Congress.

Thompson started his career as a certified public accountant and graduated from the University of Iowa. He lived in the Minneapolis suburb of Maple Grove.

His wife, Paulette Thompson, told NBC News that her husband said some people had been threatening him. She did not have details, but suggested they may have involved issues with insurance coverage.

Maple Grove Police Chief Eric Werner said his department had not received any reports of threats against the executive.