'I can't sleep at night': Neighbour first on scene of Christchurch explosion says memory haunts him

Bradley Culver's life was turned on its head at 10.14am on Friday.

The Marble Court resident was sitting on his couch watching television when his neighbour's house exploded.

Culver, a former police officer, was one of the first on the scene and helped rescue the trapped survivors from the mangled home.

Three days later, the impact of the things he saw that day continue to play on his mind.

"I haven't slept for two days, I can't sleep at night - I keep seeing the victims that we pulled out when I try to go to sleep," he said.

"We've had great support from the community, my wife's school community, my work community ... but you don't know what to say, what you need."

Residents neighbouring the property have not been allowed home over the weekend. Photo / Hayden Ivory

Six people were injured in the blast, one is still fighting for their life at Christchurch Hospital in a critical condition.

A Canterbury District Health Board spokesperson said three others were also at the hospital in stable conditions, another was discharged on Friday.

Meanwhile, a patient who was described as stable was transferred to Middlemore Hospital in Auckland where there is a serious burns unit.

Several neighbouring houses suffered major damage, including blasted walls, caved-in garage doors, smashed windows and eaves.

Culver's property is one of those, and while he and his wife were allowed home, it's uninhabitable.

"Our house is one of the ones that will not have power or gas - our house [is] shut off at the main access point to the property," he said.

"The roof is leaking everywhere because it raised up and came back down, it's leaking all over the place on to our belongings."

The scene of the serious gas explsion on Friday. Photo / James Looyer

A gas contractor who worked on the house which exploded on Thursday fronted police officers on Friday.

He made himself known voluntarily and suggested to first responders they might want to talk to him - sources said he was devastated by what happened.

A police spokesperson said they are only physically preventing access to house number nine - the affected property.

"The occupants of the other houses are being referred to their insurance and the council," they said.

"There will be police and Armourguard in the area overnight providing security and assurance to people in the affected area. [Another] cordon is still in place."

Meanwhile, Culver said his wife had been his rock during the rough few days since the explosion and was glad they were together: "that's the important thing".