Christchurch fire: 'I can't see us operating from here any time soon'

Firefighters are dampening down hotspots at a central Christchurch fire which tore through parts of an industrial building and sent smoke pouring over the city Thursday morning.

The fire is contained but is still burning after starting in the industrial complex on the corner of Colombo Street and Cass Street, in the suburb of Sydenham, just before 4.30am.

A Fire and Emergency spokesperson said investigators would examine the scene Friday and there was no confirmed cause as yet.

At its peak 50 firefighters and 10 fire trucks were battling the Sydenham blaze.

Six people were injured with two of them taken to hospital, and an alert sent to residents and businesses' cellphones in Sydenham, Addington and Spreydon told them to keep their windows and doors closed to avoid the smoke.

The spokesperson said firefighters were wrapping up their operations but a crew would continue dampening down hotspots before handing the building back to its owners later tonight.

Auto Inspection Services owner Nick, who did not wish to provide his last name, said his business was a "quite a mess" and he would likely need to move.

"It started next door at one of the tenants and spread through the roof," he told RNZ this evening.

He understood a lithium battery was the culprit after someone had disposed of it inappropriately and it had caused other waste to catch fire.

It then climbed into the building's roof before spreading through to his business.

A spokesperson for Enviro NZ confirmed its facility had been damaged, but it was unclear what caused the fire and too early to speculate on where it had started.

Phoenix Recycling Group, another tenant of the complex, confirmed it had not been involved in the fire and its premises was unaffected.

"The cause of the fire is unknown, and our premises and staff have not been affected. Our staff have been sent home for the day and they will only be allowed to re-enter the premises once the authorities have informed us it is safe to do so."

Earlier, firefighters said they believed the blaze spread from a pile of waste and general rubbish, but said it was not clear how it started.

Nick also moved to dispel rumours he had seen online that an electric vehicle in his shop was the cause.

"I have been definitely assured it didn't start at our premises. It didn't start in a vehicle," Nick said.

"We have one electric vehicle on site which is my work vehicle and it's completely undamaged."

The damage to his business was significant and he expected it would need to relocate.

"I can't see us operating from here any time soon."

Christchurch's Hagley College closed for the day because of the smoke coming from the fire.

Fire and Emergency Incident controller Dave Key told media Thursday morning the fire was contained but still burning.

Firefighters knew where the fire began but were still investigating what caused it, he said.

Roads around the workshop were closed as a result of the blaze.

Crews would be at the scene all day and using heavy machinery to turn over the site.

That meant the smoke would be coming and going throughout the day, Key said.