Story highlights Bettie Jones, 55, and Quintonio LeGrier, 19, were fatally shot by Chicago police

LeGrier's family says he was mentally ill and threatening with a baseball bat

(CNN) Chicago police said a 55-year-old woman was "accidentally struck and tragically killed" by an officer Saturday.

The woman, Bettie Jones, and Quintonio LeGrier, 19, were both shot and killed after police responded to a domestic disturbance call.

"Upon arrival, officers were confronted by a combative subject resulting in the discharging of the officer's weapon which fatally wounded two individuals," Chicago police said in a statement.

"The 55 year old female victim was accidentally struck and tragically killed. The department extends it's deepest condolences to the victim's family and friends."

The officer will be on administrative duty for 30 days while an independent police review authority investigates, Chicago police said.