UnitedHealthcare CEO Brian Thompson fatally shot in New York

Brian Thompson, the CEO of UnitedHealth Group's insurance unit, was fatally shot outside the Hilton Hotel in midtown Manhattan Wednesday morning, in what is believed to be a targeted attack, a person familiar with the matter told CNBC.

UnitedHealth Group canceled its investor day after reports emerged of the shooting. Thompson led UnitedHealthcare, the largest private health insurer in the U.S.

The suspect is described as a white male wearing a black hoodie, black pants, black sneakers with a white trim and a grey backpack, the person said. The suspect is also described as using a firearm with a silencer, the person added.

A spokesperson for the New York Police Department confirmed that a 50-year-old male was shot in front of 1335 Avenue of the Americas in midtown Manhattan at 6:46 a.m. ET on Wednesday. But the spokesperson did not confirm the identity of the man.

A formal report from the department said upon arrival, the man was unconscious and unresponsive with a gunshot wound to the chest. Emergency medical services responded and transported the man to the Mount Sinai West hospital in critical condition and he was later pronounced deceased.

No arrests have been made and an investigation is ongoing, they added.

UnitedHealth Group was hosting its investor day at the New York Hilton hotel in midtown. UnitedHealth Group did not immediately respond to a request for comment.

The company did not confirm the shooting during its investor day.

"I'm afraid that we – some of you may know we're dealing with very serious medical situation with one of our team members," UnitedHealth Group staff 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."

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