Police say an Auckland woman was killed after a gas explosion in a tunnel in Onehunga on Saturday morning.
A man remains in a critical condition in intensive care after the explosion, while three other men have been released from hospital.
Six men were injured in a gas explosion in a Watercare Services tunnel beneath the corner of Victoria and Mt Smart roads at about 8am.
Police say a crew of seven were about four metres inside the tunnel, which is about three metres deep.
Two were blown outside by the explosion. Fire crew with special breathing equipment pulled out the others.
A woman, 48, is dead and six other workers were taken to Auckland hospital.
Residents say they felt the ground shake and saw a helmet flying 20 metres along the street.
One man critical but stable
An Auckland hospital spokesperson said three of the crew had been discharged by Saturday afternoon.
The hospital's director of Trauma Services Dr Ian Civil says the three men still in hospital have sustained blast, penetrating and blunt trauma injuries.
He says one man has severe injuries and underwent surgery for several hours, and on Saturday night was in a critical but stable condition in intensive care.
Dr Civil says a second patient has moderate injuries and the third has minor injuries but is being kept in hospital for further observation and possible treatment.
He says orthopaedic and vascular surgeons were involved in assessing the three patients.
Aucklanders urged to conserve water
Watercare Services is urging Aucklanders to conserve water after the incident as a precaution.
Its chief executive Mark Ford says the watermain was shut down and the workers involved in the explosion had removed a section of the pipe.
He says until the emergency services finish their investigation, his company will not be able to reconnect the pipe.
Mr Ford says it's likely the watermain will be out of action over the long weekend and it will take a day's work to reconnect it.
He says the fatal explosion marks a very dark hour for the Auckland council organisation.
Mr Ford says many of the crew are like family and his heart goes out to all those affected by what has happened.
Gas supplies still off
Police said on Saturday evening that gas levels at the scene of the explosion remained high and emergency services would remain there overnight.
The District Commander for Auckland City Superintendent George Fraser says the cause of the explosion is still unclear and access to the area is restricted.
Mr Fraser says emergency services are pumping air into the water main in an effort to make it safe.
He says when the gas levels have subsided a thorough scene examination will be conducted and the work to reconnect the watermain will continue.
Gas supplies to streets near the tunnel have been shut off.
The Fire Service's acting area commander, Steve Lakin says they are now working with technicians on site to determine what the gas is.