A witness to a massive fertiliser plant fire in Christchurch says he heard a number of small explosions as the building became completely engulfed in flames.
Thick plumes of black smoke were seen from across the city and small explosions were heard by those nearby as the fire broke out at Ravensdown fertiliser factory in Hornby at around 10am.
Local business owner Peter McWhirter was having morning tea when the fire broke out.
He didn't hear anything at first but as the intensity of the fire built he heard a few 'minor explosions'.
"In four minutes, there was near on nothing to huge, massive [amounts of smoke]," he says.
"Having a look at it, it looked like a conveyor belt was burning because of the intensity of the black smoke. It finished up a couple of hundred metres in the sky."
After 20 minutes the building was completely engulfed in flames from one end to the other. It was "pretty much a write off", Mr McWhirter says.
Another witness, Kara Beattie, told Newshub she felt threatened by the smoke.
"There were billows and billows of smoke. I felt a bit threatened, there were only two of us in the office at the time."
"It was just billowing, it was huge."
Ravensdown chief executive Greg Campbell says the fire could have started from items on a conveyor belt but at this stage that is "speculation".
The company will be conducting its own investigation to determine the cause of the fire. Mr Campbell says the building was relatively new.
Fertiliser production will be halted but the company has two other stores, one in Dunedin and one in Napier, that will be able to produce supplies at the required rate.
No explosives were in the building, common chemicals used to make fertilisers such as urea were in the building.
Ravensdown has operated on the Hornby site since 1922.
St John, Fire and Emergency New Zealand and Police all responded to the fire.
The Canterbury District Health Board warned residents to avoid the smoke if possible and to look out for those who may be suffering health effects from inhaling it.
"Avoiding exposure to the smoke is the best advice right now. If you live nearby or downwind of the smoke plume, stay indoors and close windows. Don't use air conditioning or ventilation that will draw smoke into your home or car," Dr Cheryl Brunton says.
A section of Main South Road between Carmens Road to Springs Road remains closed.
Newshub.
