'Remain indoors': Smoke billows as large fire erupts at Christchurch workshop

A Christchurch car workshop owner says a blaze that's sent smoke over the city has left his business in "quite a mess".

About noon, smoke was still billowing from the roof of the industrial complex on Cass Street in the suburb of Sydenham.

An alert has been issued because of the smoke coming from the fire, with nearby residents warned to stay indoors with their windows closed.

At least one school was closed because of the smoke.

Six people were injured, two of whom were taken to hospital.

St John sent five ambulances and three rapid response units to the fire.

It said it treated six people in total at and near the scene, and two were taken to Christchurch Hospital in a moderate condition.

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.

He said he understood the fire was started by a Lithium battery in a neighbouring recycling plant, spreading through the roof of the complex and into his business, he said.

"It appears to me it's gone up into the roof and gone through the roof into our side of the building."

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.

"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."

RNZ attempted to contact the recycling site, but received no response.

Christchurch's Hagley College is closing for the day because of the smoke coming from a nearby fire.

In a post on Facebook, the College said they had made the decision to close because of the smoke.

"Year 9 & 10 students will be heading to Gym 2 and will be released upon a message from home being sighted. We will make a decision about After 3 later in the day."

Fire and Emergency Incident controller Dave Key said earlier the fire was contained but still burning.

50 firefighters and 10 fire engines were battling the Sydenham blaze.

Key said they know where the fire began but were still investigating what caused it.

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He said roads around the workshop would be closed for much of the day but crews aimed to get at least part of Colombo Street reopened by about 10am.

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.

Other businesses ran out of the same building that the workshop was in and would be affected, he said.

Emergency services were called to Auto Inspection Services on Colombo St shortly before 4.30am on Thursday, a Fire and Emergency NZ spokesperson said.

The large fire was still burning, the spokesperson said and part of Colombo and Durham St, around the building were closed and would remain so for some time.

A police car and ambulance were also at the site, an RNZ reporter said.

The smoke drift was affecting the Sydenham, Addington and Spreydon area, Fire and Emergency said.

It issued an emergency alert warning people to stay indoors if possible, keep doors and windows closed and be mindful about using air conditioning units.

"If you have any health concerns please call Healthline or 111 in an emergency".

At this stage it was too early to say what had caused the fire, the spokesperson said.

It was believed it would take some time to extinguish the fire due to the size of the building.

No injuries have been reported.