Detectives are probing three fires in the Springfarm housing estate in Antrim, which occurred in broad daylight on Sunday morning.
Police are currently trying to establish a motive.
At around 10am, bins were pushed up against the front doors of two addresses in Tiree Street and set alight.
A burning rag was also pushed through the letterbox of a property in nearby Arran Street.
All of the properties were occupied at the time.
However, none of the residents were injured.
Police are asking for the public’s help in identifying the person (or persons) responsible.
Police at the Antrim Reactive and Organised Crime can be reached by calling 101, or information can be given anonymously via Crimestoppers by ringing 0800 555 111.