ST. LOUIS (AP) — St. Louis County Prosecuting Attorney Wesley Bell is asking for patience during the investigation of a fatal officer-involved shooting near a large shopping mall.

A Richmond Heights, Missouri, police officer on Saturday killed 23-year-old Terry Tillman. The officer saw Tillman, who was black, inside the St. Louis Galleria carrying a gun. Concealed carry is legal in Missouri, but the mall prohibits weapons.

Authorities say the officer confronted Tillman, who ran outside. The officer chased him to a parking garage, where the shooting occurred.

St. Louis County police say a weapon was recovered but released few other details.

Prosecutor Wesley Bell says in a statement Tuesday that a “thorough and detailed” investigation is occurring.

Two people were arrested Monday for blocking a street during a protest over the shooting.