Sounds like they responded to a domestic violence call, went into the house and "Carnicle and two officers were standing on the stairs outside the apartment. The suspect opened the door and opened fire on Carnicle and the two other officers."
The commander (Carnicle) had 31 years of service and was retiring from the force in just a few months, the other 2 officers were wounded but are expected to recover. The shooter shot at a police drone and some reports say he shot at other police officers who arrived on the scene, but I'm not sure if that was verified.
He was however later shot and killed by police. What a sad deal.
https://twitter.com/PhoenixPolice/status/1244482464283684864