ST. LOUIS (AP) — A St. Louis police officer has been charged with involuntary manslaughter in the shooting death of a fellow officer while authorities say they were playing with guns.

Circuit Attorney Kim Gardner on Friday announced the charge against 29-year-old Nathaniel Hendren in the death of 24-year-old Katlyn Alix.

Alix was with two male officers at an apartment when she was killed early Thursday. A probable cause statement from Gardner’s office says Hendren and Alix were “playing with firearms” when the shooting occurred.

The men drove her to a hospital where she died.

The two male officers were on-duty at the time. Alix was off-duty. Police Chief John Hayden has declined to answer questions about why the officers had gathered at the apartment, which was home to one of the men.

A message seeking comment from police was not immediately returned.