Police say the teen ignored repeated commands to drop a gun before Officer Cedric Elleby fired four times, last Thursday striking the boy as he ran away.

At a news conference Tuesday, Police Chief Michael Harrison reiterated the department’s use of force policy.

“The decision to use deadly force is always based on reasonable, proportionate and necessary,” said Harrison. “The officer has to determine that in a nanosecond, but it's based on the threat and the potential of threat.”

The investigation remains active, while Elleby is on standard administrative leave. He has not yet given his account of what happened.

Harrison said there are strict rules that include state law when asked why the officer has not yet been interviewed. The agency is awaiting a medical report and will do a thorough investigation, he added.

Police did not say what charges the teen will face.