Police are piecing together the events that led to last night's raid and torching of the Dunwich Post Office in which a 45-year-old woman was bashed.
Police said the post office was robbed, set on fire and the postmistress punched in the face after five balaclava-clad bandits raided the post office at 3.20am, while her husband was out fighting a fire at the nearby school.
Police believe the robbers set a fire in a bush and in the library of the Dunwich school in Bingle Road as a diversion to get the post master away from the post office.
Auxiliary fire fighters, including the post master, were dealing with the two fires when they were alerted to a fire at the post office in Wellesley Street at 3.20am.
It is believed the five balaclava bandits broke into the post office and the adjoining residence and forced the wife of the post office operator to open the safe.
It is understood she was bashed before the bandits set the building on fire.
The woman was taken to Dunwich Hospital with facial injuries and concussion.
The post office and residence was destroyed by fire.
The school classroom was damaged by smoke.
Several nearby homes were evacuated during the fires.
Fire crews from Redland Bay were also sent to the island to backup the auxiliary firefighters from Dunwich and Point Lookout.
Police and fire investigators are still at the scene.
Wynnum District Acting Superintendent Gerry Costello is on Stradbroke Island overseeing the investigation and held a press conference this afternoon.
The Dunwich man was taken to Cleveland for further questioning.