Body camera footage released this week captured the confrontation.
Duncan yelled and threw things at officers before reaching into the bags she was carrying. She refused commands to show her hands and continued to walk away.
Officers followed her with a cruiser for a quarter mile, and Duncan kept refusing commands to surrender.
“I believe she has a gun,” one of the officers as they walked.
When Duncan reached an intersection, she drew a gun and fired a shot at officers. The round struck a cruiser’s driver’s side door, and the responding officers opened fire.
Duncan was struck in the exchange, and she was pronounced dead at the scene.
The shooting still remains under investigation.