Auckland wharf explosion: Hawkins construction working to find cause of blast

The construction site company where five people were badly burned in an explosion this morning say they are a tight team and its immediate focus is on the injured workers, their whānau and those they worked alongside.

But a union leader has this afternoon also called for a "full investigation" into the incident at a Hawkins wharf building site in central Auckland's Wynyard Quarter, saying "every New Zealander deserves to know they will be safe at work".

"Clearly on this occasion the health and safety system operating at this workplace has not kept workers safe and needs to be put right as quickly as possible," NZ Council of Trade Unions' president Richard Wagstaff said.

"It's important there be a full and detailed investigation into how this happened and steps are taken to better protect workers."

The blast - suspected to have been caused by a gas cooker left on overnight - knocked some people out of their shoes and shredded clothing remained at the scene.

All five injured were in Middlemore Hospital tonight, with one of the injured having been transferred this afternoon from Auckland city Hospital.

Two are in critical but stable condition, a Counties Manukau Health spokeswoman said.

The remaining three, including the person transferred from Auckland City, are in stable condition.

Hawkins spokesperson Helene Toury earlier confirmed the incident occurred at their site.

"Our immediate focus is to support the injured workers, their whānau and the team onsite. We are working with the relevant authorities to establish exactly what occurred."

The company was grateful for the efforts of the first responders - Fire and Emergency New Zealand, the New Zealand Police and St John New Zealand, Toury said.

"We are a tight team and our thoughts are with the injured workers and their whānau."

The company couldn't comment on today's events until the incident investigation was completed.

Shredded items of clothing where injured workers were treated on the Halsey St footpath. Photo / Michael Craig

Wagstaff said it was lucky no one was killed.

"Sadly, our construction sector has a terrible record of workers being killed or injured on the job."

Eleven workers were killed in construction just last year and 4800 had an injury requiring more than a week away from work, he said.

The construction industry was a substantial and significant employer.

"WorkSafe must act swiftly to get to the bottom of what has gone wrong."

The incident triggered a large-scale response from emergency services who raced to the Halsey St site about 6.30am.

WorkSafe has been notified and has opened an investigation.

A spokesperson said as it was currently making inquiries as part of the investigation it couldn't comment further.

Five injured in the blast were taken to Auckland hospitals for treatment. Photo / Michael Craig

Four people with serious injuries were transported to Middlemore Hospital and one person with moderate injuries was taken to Auckland City Hospital.

Eyewitnesses reported seeing firefighters douse the victims with hoses as they awaited ambulances.

A large-scale emergency response in Halsey St just after 6.30am. Photo / Michael Craig

Auckland Central Station senior station officer Frank Walsh told Stuff firefighters were the first to arrive at the scene.

"On arrival, we were confronted with five quite badly burnt patients down by the side of what appeared to be a shipping container.

"We arrived before the ambulances, so had to triage the patients and administer first aid, including beginning to cool the burns."

The Halsey St construction site at the scene of the early morning blast. Photo / Michael Craig

He said firefighters directed water on the burns with fire hoses.

A man who had worked with those injured told Stuff the explosion happened inside a portacom at the site.

"One of the boys was cooking some leftover meat last night and I think the gas cooker must've accidentally been left on."

Work had not started at the Hawkins construction site on Pakenham St West when the explosion occurred. Workers were sent home and the site was closed today with the site posing no further risk to the public.