Officer Lora heard the crash from inside his home and ran outside. He was wearing civilian clothes and was carrying his police-issue 9-millimeter Glock handgun. The officer had his badge clipped to the waistband of his jeans, witnesses said.

By the time he arrived at the accident scene, many people had gathered around the minivan, witnesses said. Officer Lora told investigators that when he approached the vehicle and opened the driver’s side door, he found that Mr. Arzu was irrational and unresponsive to his questions and commands.

The officer said that it appeared as if Mr. Arzu was intoxicated, and that he failed to produce his driver’s license. Witnesses said the two men were heard yelling at each other. At one point, the officer said, Mr. Arzu reached for the glove compartment. No weapon was found in the vehicle.

Officer Lora told investigators that Mr. Arzu tried to close the minivan’s door and then began to drive away slowly, pulling the officer, who was partly in the van, with him. After finding that he could not free himself, Officer Lora lost his footing and began to shoot, according to the account he gave to the authorities.

After a few moments, he was able to extricate himself from the minivan, and the vehicle continued moving forward for about two blocks before it struck another car, hit the wall of a church and a pole and caught fire.

Mr. Arzu, who was not burned, was killed by a bullet that struck him in the back and pierced his heart, lung and aorta. Four other bullets were found lodged in the minivan.

Mr. London, Officer Lora’s lawyer, said that his client, a member of the department’s Manhattan Traffic Task Force, is a nine-year veteran of the department. A married father of a 2-year-old child, he is former marine and a veteran of the Persian Gulf war.