UnitedHealthcare CEO Brian Thompson was shot and killed Wednesday morning in New York City, where UnitedHealth Group (NYSE: UNH) was hosting its annual investor conference.

New York City Mayor Eric Adams called it a “targeted murder.” The city’s police commissioner, Jessica Tisch, also described it a “brazen targeted attack.”

UnitedHealth Group is one of the largest companies in the country, and the largest health care company. UnitedHealthcare, which Thompson led, is the company’s insurance arm. UnitedHealthcare is the largest Medicare Advantage (MA) administrator, meaning it works regularly with home health providers across the country.

Optum – UnitedHealth Group’s provider services arm – owns LHC Group, a top home health provider in the country. Optum also agreed to acquire Amedisys Inc. (Nasdaq: AMED) last year, though that deal has not been finalized.

UnitedHealth Group’s investor conference abruptly ended on Wednesday after news of the shooting surfaced.

“We are deeply saddened and shocked at the passing of our dear friend and colleague Brian Thompson, the CEO of UnitedHealthcare,” UnitedHealth Group said in a statement. “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. Our hearts go out to Brian’s family and all who were close to him.”

Thompson had served as the CEO of UnitedHealthcare since April of 2021. Previously, he ran government programs for the insurer. He had been with the company since 2004.

At the UnitedHealthcare headquarters in Minnetonka, Minnesota, flags were lowered to half-staff to honor Thompson.

New York City police have offered a $10,000 reward to anyone with relevant information regarding the shooting.