The Sean Bell case has been invoked after a man was shot by an off-duty police officer while driving in the Bronx Friday.

Family members of the driver, Fermin Arzu, yesterday brought up Bell, who was shot by police while driving in Queens last fall, after a gathering called by the Reverend Al Sharpton near where Arzu was shot by a Manhattan transit officer.

“Just because they had a little power they decided to take someone’s life,” a niece of Arzu, Desiree Melendez, 22, said, referring to the transit officer, Raphael Lora, and to the detectives accused of shooting Bell.

Rev. Sharpton, who has led numerous protests over Bell’s death, was traveling to meet with elders of the Mormon Church in Utah yesterday and did not attend the gathering.

Police and neighbors said Mr. Lora followed Arzu after he drove away in a minivan he had just rammed into a car parked in front of the officer’s house on Hewitt Place. Mr. Lora then fired a shot that punctured Arzu’s heart and lung, according to the medical examiner.

The president of the Patrolman’s Benevolent Association, Patrick Lynch, yesterday warned against making “snap judgments” before an investigation was completed, while neighbors of Mr. Lora praised him as a kind neighbor who had made the neighborhood safer.

“There were gangs,” a 20-year resident of the block, Berta Camacho, 79, said. “It helped to have a policeman here because there was a little more respect.”

She said Mr. Lora had often shooed away people who played loud music on the street. Before becoming a police officer, Mr. Lora served in the military, Ms. Camacho said.

Mr. Lora has been reassigned to unarmed duty, a spokesman for the police department, Deputy Commissioner Paul Browne, said. He said police were cooperating with the prosecutors in an investigation.