The site of the gas explosion in Onehunga, Auckland. Sourced from twitter user @PeteDaPalagi/Pete Marsden .

Media converge on the gas explosion at Onehunga, Auckland. Sourced from twitter user @PeteDaPalagi/Pete Marsden.

The scene of the gas explosion in Onehunga, Auckland. Sourced from twitter user @PeteDaPalagi/Pete Marsden.

The scene of the gas explosion in Onehunga, Auckland. Sourced from Twitter user TV One reporter Jack Tame.

On the scene of the Onehunga gas explosion.

Emergency workers at the scene of a gas explosion in Onehunga, Auckland.

Emergency workers at the scene of a gas explosion in Onehunga, Auckland.

Emergency workers at the scene of a gas explosion in Onehunga, Auckland

Emergency workers remove a body from the scene of a gas explosion in Onehunga, Auckland.

Emergency workers at the scene of a gas explosion in Onehunga, Auckland.

Emergency workers remove a body from the scene of a gas explosion in Onehunga, Auckland.

Emergency workers remove a body from the scene of a gas explosion in Onehunga, Auckland.

A body is removed from the scene of a fatal explosion in the Auckland suburb of Onehunga.

Rescue workers at the site of the gas-related blast in Onehunga.

Speaking at a Onehunga explosion press conference (front left) Derrick Adams, CEO of HEB Contractors, Mark Ford, CEO of Watercare Services and Auckland mayor Len Brown

Tony Misiagi, Joe Haare and Ramon Milner fortunately arrived late to work in Onehunga on Saturday morning.

A body is recovered by emergency services in Onehunga on Saturday morning.

PR shot of Philomen Gulland on her descent into a tunnel.

PR shot of Philomen Gulland, who died in a blast in an Auckland tunnel on Saturday morning.

PR shot of Philomen Gulland, who died in a blast in an Auckland tunnel on Saturday morning.

MEN AT WORK: Firemen sort out breathing aparatus at the site of an underground explosion in Onehunga.

HEAVY LIFTING: Firemen sort out breathing aparatus at the site of an underground explosion in Onehunga.

SORTING EQUIPMENT: Firemen sort out breathing aparatus at the site of an underground explosion in Onehunga.

Police have confirmed a 48-year-old Auckland woman was killed this morning when an explosion occurred in an underground water mains pipe in Onehunga.

District Commander for Auckland City, Superintendent George Fraser said: "The cause of the explosion is still unclear and gas levels remain high, restricting access to the area.

"Emergency services remain at the scene and air is being pumped into the space in an effort to make it safe so that a thorough scene examination can be carried out and to enable the maintenance work to continue as scheduled."

"We will be working through the night to try and ascertain how exactly this tragedy occurred."

The blast happened at an underground watermains worksite. St John spokesman Brett Tobeck said the critically-injured man had suffered partial amputations of both legs. One other person had burns and a back injury and the other four had moderate injuries.

Earlier reports said as many as three people had died, but police later said that only one person was confirmed as dead.

Auckland Hospital says it is too early to know if a critically-injured man will fully recover from this morning's blast in Onehunga which killed a person.

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Director of trauma services Ian Civil said "it is always hard to tell the degree of recovery patients with critical injuries are expected to make, and there is obviously physical and psychological recovery that needs to be considered".

"It is too early whether they will make a full recovery or not."

Emergency services have been unable to reach the scene of the fatal underground explosion.

The critically injured man is still in the operating room. He was taken to theatre this morning at 10am, an hour after he was admitted.

Five other patients were admitted to Auckland hospital this morning - three have been discharged with minor injuries, two have been admitted to general wards.

Civil said most critically injured people take "weeks or months to fully recover, I would imagine the same will apply in this case".

He said there were "no signs of gas that affected our ability to resuscitate and assess the patient".

Civil said explosions usually resulted in a combination of blast, penetrating and blunt injuries.

''[Blast injuries are] commonly seen in war time scenarios where there is a pressure wave that affects the patient and on the air containing organs like the lungs and the bowel.

''We haven't found much evidence of blast injuries at the moment but it is early days.''

Penetrating injuries occur when someone is hit by objects thrown through the air and blunt injuries when they land or get thrown themselves.

Auckland hospital were called this morning and told there had been a gas explosion in a pipe and there was a death at the scene.

"We were told that there was at least one person dead and a number of other patients with serious injuries that they were bringing to Auckland Hospital.''

The blast happened about 8am on Mount Smart Rd.

Steve Lakin, Acting Area Commander for the Auckland Fire Service, said testing still needed to be carried out to determine which gases might be present at the scene. However, he said current levels of gas were not considered to be dangerous and local residents were not in danger.

At this stage, he said "we can't get to where we need to be" to determine which gas was present at the site.

Police Superintendent George Fraser confirmed that one worker had died and six had been taken hospital. Lakin said the explosion "threw two workers out" of the blast scene.

Auckland Mayor Len Brown attended the scene during the morning as did local MPs Carol Beaumont and Sam Lotu-Iiga.

Victim support services also arrived to speak with local residents.

Emergency services remain at the scene which police said had been made as safe as possible, while work continues to determine the cause of the explosion.

Aucklanders are being urged to conserve water over the long weekend.

Watercare chief executive Mark Ford said it could take up to 10 hours to reconnect the affected water main.

In the meantime residents should keep water use to a minimal.

Ford said a water shortage was unlikely because reservoirs were full and demand generally drops over holiday weekends when people go away.

"I'm confident this will not impact water supply."

The workers caught up in the blast were from HEB Construction and were working on a watermain connection on behalf of Watercare Services - an Auckland Council controlled organisation.

A reporter at the scene said firefighters were seen carrying two people, covered in cloth, from a trench in the road.

"There is a very large hole in the road and fire rescue crews are working in it. It appears to be a reasonable depth and half the road wide."

The blast threw debris and dust around the construction site.

A large number of emergency service crews were at the scene, including a specialist fire unit. Firefighters could be seen setting up flood lighting equipment.

St John spokesman Brett Tobeck said the man with critical injuries had suffered partial amputations of both legs. One other person had burns and a back injury and the other four had moderate injuries.

Watercare Services confirmed the explosion was in a trench where contractors were connecting a new watermain to an existing watermain. Distressed family members of the contractors were gathering at the scene.

The new watermain, called Hunua 4, would eventually run from the Redoubt North Reservoir in Manukau to Market Rd in Epsom, connecting to the local water supply network at various points along the way.

Watercare said it chose this weekend to make the connection because there would be less traffic and less demand for water over the three-day holiday period.

Chief executive Mark Ford said it was a ''dark hour'' for the organisation.

"It is with deep sadness that I confirm there was a serious incident at the site. This is a very dark hour for us - many of the crew on site are like family to us, and my heart goes out to all of those affected by what has happened."

Ford spent time with the seriously injured and their families at the hospital.

Ford said contractors were working to join two large water mains at the intersection of Mt Smart Rd, Victoria St and Athens Rd, Onehunga, about 8am when the explosion occurred. Watercare staff were also on site to inspect the work.

Ford said emergency services were quick to respond and were continuing to work on site. An investigation into the cause of the explosion was ongoing.

"We are not in a position to say at this stage what caused the explosion however we are working closely with the contractors and all the authorities, including the police, fire service and the Department of Labour."

Carol Beaumont, a local MP, said this weekend the workers were connecting the water pipelines up. She said it was a major project.

Watercare had a "comprehensive plan for the project this weekend ... they would of had a risk assessment in place".

Tamati Kaiawe, 17, was walking past the site when the explosion happened. He has explained to media how he saw mud fly out of the hole and then heard people screaming for help. He said emergency services arrived within about 10 minutes and were "straight in there".

A resident who lived about 200m away, Ray Tema, went down to the scene when he saw emergency services arrive.

"I saw two helmets lying on the road about 10 metres away."

Josh Pasa, who lives about 500m from where the explosion happened, said his wife drove down Mt Smart Rd about 3am and saw workers at the site, where they have been working since February to replace the water main.

Pasa said he spoke to the workers last night and they had planned to turn off the gas main so they could start early.

Stuff reader Esther Montgomery lived a few houses down from where the explosion happened.

"My bedroom windows actually moved and shook violently for about 20 seconds. We thought there was an earthquake."

Other residents have told Stuff how there was a massive explosion about 8am many said it felt like an earthquake.

- Stuff, with NZPA

