The gunman who killed UnitedHealthcare CEO Brian Thompson in a brazen ambush outside a New York hotel is believed to have left the city shortly after the attack, possibly on a bus.

The police have not identified the shooter or established a motive, though they are considering the possibility of a disgruntled employee or client.

The suspect, who concealed his identity with a mask, was captured on video fleeing the scene and later taking a taxi to a bus terminal.

Investigators found a backpack he left behind in Central Park, which may contain valuable clues. The FBI is offering a $50,000 reward for information.

The shooting, which has deeply shaken the corporate world, involved a gun equipped with a silencer and ammunition marked with words linked to insurance claims, leading investigators to suspect the gunman’s grievance was related to the insurance industry.

Thompson, who had been with UnitedHealthcare for 20 years, was shot multiple times outside the company’s annual meeting, the Associated Press has reported.

The incident has prompted heightened security concerns across the health insurance sector.

Written by B.C. Begley