After being evacuated safely, the occupants were treated for minor injuries.
Two crews remain at the scene, and a fire investigator will examine the cause this morning.
Police said they will be working with Fire and Emergency investigators to “understand the circumstances surrounding the fire to determine next steps”.
Fire and Emergency was also alerted to a private smoke alarm at a 15-storey residential building in Auckland City Centre around 5am.
Nine crews responded after smoke was reported on level four.