Gunman who killed Brian Thompson, UnitedHealthcare CEO, is on the loose. What we know about the suspect.

NEW YORK — A manhunt is underway in New York for the gunman who shot and killed UnitedHealthcare CEO Brian Thompson on Wednesday morning in what police sources said appeared to be a targeted attack.

Thompson, 50, was shot once in the chest around 6:45 a.m. outside the Hilton Midtown hotel on Sixth Avenue near West 54th Street in New York City, NYPD sources said. Thompson was not a guest at the Hilton, according to NYPD sources. He was staying at another hotel and was walking to the Hilton for a corporate event when he was attacked.

A spokesperson for UnitedHealthcare told CBS News the shooting took place during the company's investors conference.