It began about 6:40 Thursday night near 109th and South Eberhart. Police responded to a domestic-related call.
They were told a woman was armed with a knife and was possibly under the influence of drugs.
Officers say as they entered the apartment, 60-year old Angelique Styles refused orders to put down the knife.
They opened fire when they say she lunged at them. The woman was killed. No one else was hurt.