Two 13-year-olds have turned themselves over to police after a blaze gutted a seven-storey heritage building in central Sydney, officers said Friday.
Australian police said an arson investigation had been launched after Thursday's fire at a vacant former hat factory, which spread to an adjacent building and forced mass evacuations before being extinguished.
A group of young people were "seen running from the fire scene shortly after 4 pm", assistant commissioner Paul Dunstan said.
"Two young people handed themselves in at two separate police stations in the late hours of last night."
"We are speaking with these young people throughout the evening and they are now assisting police with our inquiries," he added, saying both were 13 years old.
He called on three or four other "young people who were present during the fire" to come forward with their parents to "put their side of the story forward".
Shortly after the blaze erupted, flames higher than the building and a thick column of smoke could be seen across Sydney.
The entire top floor wall toppled and crashed into pieces on the street below, fire service video showed, as the building glowed orange with flames.
Rush hour transport to and from nearby Central Station had to be stopped as firefighters tackled the blaze.