A St John spokesman confirmed one patient had been taken to Dunedin Hospital last night by ambulance and another by rescue helicopter.
Detective Sergeant Dave Nelson said a man and a woman were admitted to hospital after the incident at Portobello Village Tourist Park.
Initial enquiries indicated the pair were overcome by LPG gas.
One person is expected to be discharged today.
Stuff reported the woman was able to leave the caravan and raise the alarm.
The owner of the holiday park declined to comment.