Brian Thompson, the CEO of major insurance group UnitedHealthcare, was shot to death at point blank range in Midtown Manhattan on Wednesday morning before he was set to attend an investor conference, according to police sources.

       The masked gunman, who remains on the loose, appeared to be lying in wait and shot Thompson several times, sources said.

       The shooting, which was reported around 6:40 a.m., appears to be targeted but police do not know why, sources said.

       "This was not a random act of violence," New York City Mayor Eric Adams said. "It appears as though it is a targeted murder."

       Thompson was in New York City for the UnitedHealthcare investors conference and his schedule was widely known, police sources said.

       The conference was being held at the Hilton outside of which he was shot, but he was not staying there, sources said. The hotel is by the intersection of West 54th Street and Sixth Avenue.

       The conference was scheduled to start at 8 a.m. ET and the gunman appears to have arrived hours beforehand, according to police sources.

       The shooter appears to have known which door Thompson was going to enter, with the CEO shot several times at point blank range in the doorway on West 54 Street, police sources said.

       The suspect ran north through the midblock alleyway by the Ziegfeld Ballroom, located across the street from the Hilton, and then jumped on a bicycle and fled, police sources said.

       "We are just so sad right now," Elena Reveiz, the sister of Thompson's wife, told ABC News by phone.

       Reveiz said she was especially worried about Thompson's two children and called the CEO a good father.

       UnitedHealthcare's parent company is UnitedHealth Group, the largest health insurer in the world.

       Thompson lived in Minnesota, where the company is based.

       "This is horrifying news and a terrible loss for the business and health care community in Minnesota," Minnesota Gov. Tim Walz tweeted. "Minnesota is sending our prayers to Brian’s family and the UnitedHealthcare team."

       The gunman, who was wearing a ski mask, is described as a skinny man wearing all black who stands at about 6-foot-1, police said.

       Police are canvasing for surveillance video, sources said.

       This is a developing story. Please check back for updates.

       ABC News' Mark Crudele and Miles Cohen contributed to this report.