NSW Police say a third boy is assisting detectives with the ongoing investigation into what caused the fire that ripped through a historic inner-city Sydney building on Thursday.
The 12-year-old was in the multi-storey building at the time the fire started on Randle Street, Surry Hills, along with two 13-year-olds.
The two teens had already been co-operating with Strike Force Strontium, set up to investigate the incident, after handing themselves in to two separate police stations late on May 25.
