A steel grass roller blew up after it was put on a Mosgiel bonfire last night, injuring up to six people.
The fire service and St John Ambulance attended the 1.30am explosion on Dukes Rd North, which caused the clothing of six partygoers to catch fire, causing status two and three burn injuries to three people.
The fire also spread to a hedge. Partygoers jumped in a pond to put out the flames.
A Dunedin Hospital spokesman said two patients were treated and discharged last night, and a third was discharged this morning.
A Fire Service spokesman said the roller had water inside it, which exploded when it heated up.