Hundreds of messages about the fire flooded into Newstalk ZB's Christchurch newsroom - with smoke visible from across the city.
Fire and Emergency NZ said the clouds of smoke were from a controlled burn off.
FENZ said the burn off was on Charteris Bay Rd towards Diamond Harbour.
A Diamond Harbour resident said the fire was on Loudon Farm - and they could see helicopters with monsoon buckets putting it out.