Smoke is visible from a large fire on Hutt Rd in Petone.

Flames and black smoke streams from a building in Hutt Rd in Petone.

Firefighters at the scene of a large fire in Petone.

A wide shot of Petone showing the extent of the smoke from a large fire.

Crowds of people stop to look at a large fire in Petone.

Smoke from a large fire in Petone is seen from across Wellington Harbour at Mt Victoria.

Firefighters use breathing apparatus at the scene of a large fire on Hutt Rd in Petone.

A firefighter is treated for injuries at the scene of a large fire in Petone.

The owner of Racetech, David Black, in the blue shirt, can only watch as the fire burns through his property.

Firefighters at the scene of a large fire on Hutt Rd in Petone.

A firefighter was injured while fighting a large fire which broke out at Racetech on Hutt Rd in Petone.

Big plumes of smoke were seen coming from an industrial area where Racetech, a racing seat manufacturer, was on fire.

Hutt Road from Udy St south was closed off and a cordon erected as more than 45 firefighters fought to control the blaze.

The fire service had 11 fire engines at the scene fighting the fire, which was called in at 3.10pm, as well as an ambulance.

Assistant area commander David Key said the fire had been contained to the building, but they were having difficulty putting it out because of the amount of flammable materials inside.

It should be out in the next half hour, but firefighters would remain for most of the night in case of any flare ups.

Investigators would start looking into the cause in the morning.

He said the fire "was intense inside the building" and the crews which first arrived at the scene weren't able to get very close.

Wellington fire service communications shift manager Belinda Beets said firefighters could see the blaze before they arrived, and it was "quite a substantial fire."

There was initially thought to be a person missing, but they had been accounted for.

The fire service confirmed one of its firefighters was being treated for injuries at Hutt Hospital.

Spokeswoman Karlum Lattimore said support was being provided to the firefighter and his family.

She said no updates would be released on his condition until the morning.

"In the meantime, as is standard in these situations, a review of the firefighting operation will be carried out to look at what happened.

"A separate investigation will also be carried out into the cause of the fire. No one else was injured in the in fire," she said.

Racetech owner David Black said "the alarms went off and we made sure we everybody was out".

"I am feeling absolutely gutted. I've been in a few building fires before and it doesn't make you feel any better when its your own."

The building was insured, he said.

Police said there should be no disruption to any commuters travelling home from work along the Western Hutt Road.

"However people should refrain from 'rubber necking' to enable optimum traffic flow as we approach peak traffic time," a police spokesman said.

He requested people avoid travelling to the area near the Petone fire to allow for emergency services to deal with the incident as best they can.

The spokesman said traffic was currently being diverted via Riddlers Crescent and Udy Street Petone around the immediate area of the fire.

Leeana Moeahu and sister Ariana, who live opposite the fire, didn't realise it was so close to their home as they picked up son Tearii from Petone Central School.

The pair also saw the firefighter get injured in the blaze.

"It was a shock to see it. I tried to shield Tearii from seeing it - it was unexpected. You could see their facial expressions.

"They threw their gear on the ground and they were worried about their mate."