Police are investigating the death of suspect Brian Thompson

Police say a manhunt is underway for the shooter, who fled the scene on foot and then on a New York City Citi Bike.

He was last seen in Central Park. Crime Stoppers offered a $10,000 reward for information.

According to police, the suspect was wearing a black hoodie and black pants and carrying a gray backpack. The suspect is believed to have used a firearm with a silencer, a person familiar with the matter told CNBC.

UnitedHealthcare CEO Brian Thompson was on his way to speak at an investor conference when he was killed in a “premeditated, targeted attack” outside the New York Hilton Hotel in midtown Manhattan this morning.

He was hit at least once in the back and at least once in the right calf, police said, adding that the suspect “lay in wait for several minutes.”

Police said the suspect arrived at the hotel about five minutes before the shooting and fired one shot at Thompson’s back.

“The motive for this murder is unknown at this time, but based on the evidence we have to date, it appears the victim was specifically targeted,” said Detective Chief Joseph Kenny. “But at this point we don’t know why.”

NYPD Chief of Detectives Joseph Kenny told reporters that UnitedHealthcare CEO Brian Thompson appeared to have no security and was walking alone when he was fatally shot.