RNZ has learned that during the six day protest at Waikeria Prison Police fired sponge rounds at the men on the roof of the burning high-security building.
Sixteen inmates surrendered on Sunday, with some telling media they were protesting for better conditions.
Whanau members of two of the men say they've received phonecalls from their relatives.
They believe the men were injured by non-lethal projectiles used by the police.
Jamie Waea says her partner, currently placed at Paremoremo Prison, told her he had been hit.
