Three people are facing charges, and a fourth may be added, in connection with the undercover NYPD operation in Mount Vernon that resulted in the death of an innocent bystander.

Police say 61-year-old Felix Kumi, of Mount Vernon, was killed Friday afternoon by stray bullets that came from the gun of an NYPD officer. The officer was shooting at a suspect after an undercover operation went awry.

According to police officials, the undercover officer was to meet with Jeffery Aristy, 28, of the Bronx, to buy guns. They say the officer drove to the Bronx, picked up Aristy, who then told him to drive to Mount Vernon and pull over at Beekman and Tecumseh avenues.

That's when investigators say another man, Alvin Smothers, 37, jumped in the back seat, put a gun to the officer's head and demanded money. After the undercover gave up the money, officials say Aristy and Smothers fled the scene.

As the officer chased the men, NYPD officials say Smothers pointed a gun at the cop. They say the officer fired several shots and hit Smothers, but two stray bullets struck and killed Kumi.

Aristy was eventually apprehended and arrested. Aristy's wife, Ivett Cruz, and another man, Samuel Ruiz, were also arrested in connection with the operation. All pleaded not guilty Sunday to drug and weapons charges.

Police officials say they plan to speak with Smothers now that he is conscious and in stable condition at the hospital. The gun he pointed at the undercover officer turned out to be fake.

The daughter of Kumi says he was a hardworking family man, who made his living as a city bus driver. He lived with his wife and two children a few blocks away from where he was shot.

Mount Vernon Mayor Ernie Davis weighed in on the shooting by saying, "Life can be unfair sometimes, and I think this is just one of those times." He says he tried to visit the Kumi family Saturday morning, but was turned away.

Mount Vernon Police Commissioner Terrance Raynor says the robbery investigation is being handled by his department. The shooting investigation will be handled by the Westchester County District Attorney's Office, the New York State Office of the Attorney General or the Mount Vernon Police Department. The lead agency will be determined within the next several days.