Almost 30 vehicles were damaged as a fire took hold in a Whangārei Hospital carpark this afternoon.

Fire investigator Jason Goffin said they were still trying to find the cause of the blaze.

“Initial reports were of ignition of grass in a carpark by a vehicle’s exhaust.”

Goffin said CCTV would still need to be combed through before the cause would be fully known.

Twenty-seven cars were damaged in the blaze, ranging from regular petrol to several electric vehicles.

Goffin said the fire would have been aided by the wind.

There would have been some “bangs and pops” as the blaze took hold.

Goffin said no injuries had been reported and police were not treating the incident as suspicious at this stage.

A witness earlier said they believed at least a dozen cars were destroyed in the blaze in carpark 14, at the bottom of the hospital campus, about 50m from any hospital buildings.

The man, who did not want to give his name, works at the hospital’s Child Health Centre which overlooks the carpark.

“We started hearing a few small explosions,” he said.

“There was lots of black smoke and probably, in total, at least a dozen vehicles destroyed.”

He had noticed the flames in a couple of cars just after 2pm on Tuesday and called Fire and Emergency New Zealand on 111.

A witness believes at least a dozen cars have been destroyed in the blaze.

While his call wasn’t the first to 111, the fire spread from car to car before firefighters arrived.

The flames had been fanned by the steady wind, he said.

The man thought the fire probably started in just one car but spread along the row where the cars were packed in.

“It’s a very busy carpark, it’s normally full during the day.”

The fire has since been extinguished.

The man said he felt sorry for those people whose cars were affected, especially his own colleagues.

Smoke can be seen over Whangārei Hospital. Photo / NZME

A reporter at the scene said SUVs appeared to be among the vehicles burnt in the fire.

Some nearby houses were reportedly evacuated because of the risk of toxic smoke.

Whangārei Hospital remained open, according to Health New Zealand Te Tai Tokerau group director of operations Alex Pimm.

He said there are no reports of injuries and Health NZ is working with Fire and Emergency and police to ensure staff and patient safety.

Emergency services at Whangārei Hospital where a fire ignited in a carpark. Photo / Brodie Stone

Walkways and some nearby roads are cordoned off.

A nearby resident out walking down by the Raumanga Stream was stopped by police, who pulled out a rope, telling her she couldn’t go any further as it may be a crime scene.

Police have asked people to avoid the area while emergency services respond and for residents living nearby to close their windows.

Resident Harmony Muller was on her way home with her daughter when she noticed thick, black smoke.

She said she “was thinking, oh my gosh, I thought it was my house”.

Muller’s home is opposite the fire.

“We hope no one’s hurt,” she said.

While the drove of firefighters and police made Muller and her daughter feel safe, they had still found the blaze unsettling.