Chilling footage emerged Wednesday afternoon of UnitedHealthcare CEO Brian Thompson’s assassination outside a Manhattan hotel.

The clip, captured by a surveillance camera, showed the gunman opening fire at the 50-year-old insurance executive at close range after approaching Thompson from behind on a sidewalk outside the Midtown Hilton.

Thompson collapsed to the ground after two shots – and briefly turned to face his killer – before appearing to be completely prone after three shots. The gunman then walked toward the fallen Thompson and appeared to attempt to fire at least one more shot in his direction as he lay helpless on the sidewalk.

When the first shots were fired at 6:46 a.m., a passerby was just a few meters away from the shooter, who is still at large. This person fled behind the shooter, who appeared unfazed by the pedestrian’s presence and the passing cars to his left.

The unidentified attacker appeared to be dressed in all black in the clip, including a hoodie, pants and gloves. According to police, the shooter also wore a black mask and escaped by running through an alley and jumping onto an e-bike before disappearing into nearby Central Park.

The footage showed the gunman firing at least three times in 12 seconds at Thompson, who appeared to be wearing a blue jacket. After each shot, the man pulled back the slide on his pistol, indicating it was a single-action handgun.

The systematic shooting was a “targeted attack,” officials said, possibly because of Thompson’s position at the top of the world’s largest private health insurance company.

Thompson’s wife, Paulette, told NBC News that her husband had received threats related to his position – which was confirmed by a police source The New York Times.

“There had been some threats,” she said. “Basically, I don’t know, a lack of coverage? I don’t know the details. All I know is that he said there were some people who threatened him.”

Aside from the dark clothing he wore, no other information about Thompson’s anonymous killer was released by police. The NYPD is offering a $10,000 reward to anyone who provides information leading to the shooter’s arrest.

New York Police Commissioner Jessica Tisch said in a news conference that the bomber was “lying in wait” until Thompson approached the Hilton, where he was scheduled to speak at an investor meeting later that morning.

Tisch pointed out that the gunman ignored other pedestrians on the sidewalk but decided to open fire on Thompson. There were no other injuries in the incident.

“Many people walked past the suspect, but he appeared to be waiting for his intended target,” she said.

New York Police Department Chief Detective Joseph Kenny said the shooting broke out shortly after Thompson left a hotel across from the Hilton. He said Thompson had no security detail.

Thompson, a father of two, lived in a suburb of Minneapolis. He worked at Minnesota-based UnitedHealthcare for over 20 years and was recently estimated to have a net worth of around $43 million.