Brian Thompson, the CEO of UnitedHealthcare, on Wednesday morning was fatally shot outside a hotel in Midtown Manhattan. Thompson was in NYC for a company investor conference, reports said; police on Wednesday afternoon were still looking for the gunman, who was last spotted in Central Park.

Thompson’s death affects the leadership of one of the largest and most influential companies in the U.S. health care system, which intersects in various ways with the nursing home sector, including as a Medicare Advantage payer.

The insurance giant processes about a third of all the country’s patient records and conducts about 15 billion transactions a year, the NYT said in its report on the shooting. The company is the largest Medicare Advantage plan provider in the nation, per the Associated Press’ report.

Thompson, 50, spent more than 20 years working his way up the ladder at UnitedHealthcare, the insurance division of UnitedHealth Group. He has served as CEO since 2021 and managed a division that employs about 140,000 people. UnitedHealthcare offers insurance plans to employers and individuals, including those enrolled in government programs.

Since joining UnitedHealthcare in 2004, Thompson ran key businesses including Medicare Advantage operations, reports said. Prior to UnitedHealthcare, Thompson spent nearly seven years at accounting firm PricewaterhouseCoopers.

Thompson had recently received several threats, reports said, and these were being investigated by police. A cell phone was recovered from an alley where the suspect fled.

During his time at the helm, UnitedHealthcare underwent federal investigations while also enjoying profitable growth, The New York Times wrote. Congressional lawmakers and federal regulators have criticized the division for systematically denying authorization for health care procedures and treatments in nursing homes, among other care settings.

“We are deeply saddened and shocked at the passing of our dear friend and colleague Brian Thompson, the CEO of UnitedHealthcare,” the company 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.”

Tributes to Thompson came in throughout the course of Wednesday from his colleagues and other leaders in health care.

“I knew him to be a visionary leader who developed innovative ideas to take on some of the nation’s greatest challenges,” Kim Keck, president and CEO at Blue Cross Blue Shield Association, wrote on LinkedIn. “His death is a great loss for our country and for the health care industry.”