Mount Vernon Officer Christopher Ridley, 23, was trying to make an arrest outside a Westchester County government complex when officers from a different department spotted him, and, under circumstances that remain unclear, opened fire and killed him.
Ridley was not in uniform and was out of his jurisdiction, but White Plains Public Safety Commissioner Frank Straub said Saturday that the young officer had witnessed a violent assault taking place and rushed to break up the fight.
He was struggling with the 39-year-old suspect when Westchester County police officers came upon the fray. Witnesses told reporters that the officers ordered Ridley to drop his gun, then shot him when he didn't immediately comply.
The shooting happened shortly before 5 p.m., just as the streets began to fill with people leaving work.
Straub and other police officials refused to discuss the details of the shooting Saturday, and wouldn't say what prompted the county officers to shoot, how many of them shot, or how many shots were fired.
The president of the police union in Mount Vernon, Kevin Mandel, said Ridley "couldn't have done anything wrong," and praised him as a hero for trying to break up the assault.
Mount Vernon Police Commissioner David E. Chong called the slain officer "a quiet and kind soul," and said he was confident the White Plains Police Department - which operates independently from the Westchester County department - would conduct an impartial investigation.
The shooting prompted a visit to White Plains on Saturday by the Rev. Al Sharpton, who called for a thorough probe.
Ridley attended the same church in Mount Vernon as the chairman of Sharpton's civil rights group.
Speaking to reporters in front of the White Plains police headquarters, Sharpton said he didn't know whether race was a factor in the shooting.
Ridley is black. Authorities did not initially reveal the ethnicity of the officer, or officers, who shot him. Sharpton said he would reserve judgment until the facts are known, and expected investigators to do the same.
"As we are calling on the community not to rush to judgment, the police should not rush to judgment," Sharpton said. "You should not do a 12 hour investigation and say it was a justified shooting."
Ridley's father, Stanley, stood with Sharpton during the news conference but did not speak to reporters. Nearby, a group of women sobbed, "They killed our baby."
The Rev. William Mizell, associated pastor at Grace Baptist Church in Mount Vernon, remembered the slain officer as a music lover who was active in the congregation and would sometimes help children cross the street on their way to services.
"This was a young man who always had compassion for others," Mizell said. "That's how he lived and that's how he died." He said Ridley was single and had no children. Ridley's father is a custodian at the church.
Ridley joined the Mount Vernon police force in 2006.
Chong called him an officer with "unlimited potential."