Officer Krystal Rivera was excited to celebrate her daughter's 11th birthday this weekend. But Rivera's life was tragically cut short late Thursday, when she was fatally shot in the back by a bullet fired by another officer.

Police confirmed that the only person who fired a weapon during the chase was an officer, "whose gunfire unintentionally struck Officer Rivera."

A Chicago police officer shot and killed a fellow officer during a tactical operation Thursday night, police said. CPD said Friday that the only weapon discharged during a confrontation with an armed suspect in Chatham Thursday was that of an officer,