One bullet whizzed past Officer Jones’s head. She fired back, emptying her five-shot revolver. One shot knocked the gun from the man’s two-handed grip, piercing his right middle finger and grazing his left hand, according to the police. Another shot hit the lock on the front door, jamming it. The gunman tried to flee, Mr. Browne said, but could not get the door open. Finally, he grabbed his gun, kicked out a lower panel on the door and crawled out. Officer Jones followed him out the door to see which way he was running.

Mr. Browne said Officer Jones’s performance was commended at an internal police briefing by Police Commissioner Raymond W. Kelly, who said that “her reserve under fire was matched only by her marksmanship.”

Officer Jones, a native of Barbados, joined the department in 1990 and has worked the past 12 years in the evidence collection unit in the crime lab. It was the first time she had fired her gun in the line of duty, Mr. Browne said.