What we know:
- Six people were injured following a large gas explosion in the Christchurch suburb of Northwood. Their statuses range from critical to moderate.
- A house was totally destroyed, with damage caused to surrounding houses, Fire and Emergency New Zealand (FENZ) confirmed.
- At least 50 surrounding properties were evacuated.
- Gas and power were turned off to Marble Ct and Brookwater Ave.
- Debris could be seen all over the road.
- Cordons were in place and people are asked to avoid the area.
- WorkSafe will work with police and FENZ to investigate the incident.
5:02pm - An update on cordons will given by police at 5:30pm, a spokesperson says.
4:55pm - The nearby Styx Mill Country Club says there is no time frame for when residents may be allowed inside the cordon to return to their homes.
The cordon however has been lifted for odd-numbered houses on Millstream Dr.
4:15pm - The Canterbury District Health Board has provided an update on those injured in the explosion.
A spokesman said one person remains in a critical condition, while three are stable, and another has been discharged.
It's been confirmed the sixth person injured was transferred to Auckland's Middlemore Hospital.
3:50pm - A Christchurch Transport Operations Centre spokesperson says a number of road closures have been requested by police.
The public is still asked to avoid the area, the spokesperson said.
Marble Ct, Brookwater Ave, and Millstream Dr will be fully closed until further notice. Springbrook Ln, Brookfield Dr, and Water Mill Blvd are partly closed.
3:45pm - Resident Ann Gray says the explosion felt scarily similar to a strong earthquake.
"The whole sky was just full up with wood and debris from this explosion," she told Newshub.
3:40pm - It is believed a gas fire inside the house at the centre of the explosion was causing problems this week, relatives told Stuff.
Belinda Blanchfield's parents and three others were inside the house at the time of the explosion. She told Stuff: "It's our worst nightmare. My parents are the absolute kindest people ever. A very, very close family."
3:30pm - One resident told Newshub he was having a shower at the time of the explosion, when the glass frame started to crack.
"It literally just started falling apart," he said.
3:15pm - News about the large gas explosion which turned a has spread across the world, with Canadian and British media outlets picking up on the incident.
3:00pm - Resident DeArna McCaskey says at first, she thought the explosion was a plane crash.
"I saw people comforting the people that got injured," she added.
2:45pm - WorkSafe confirms it will be investigating the explosion, and working with police and FENZ.
"As the matter is now under investigation, we are unable to comment further," a statement said.
2:40pm - The Canterbury District Health Board says it won't be addressing the media following the explosion.
Five injured people were taken to Christchurch Hospital, and Newshub understands the sixth injured person was flown to Auckland's Middlemore Hospital. A health board spokeswoman said an update will be provided shortly.
2:25pm - Residents say they have been left shaken by the ordeal.
"I'm actually still shaking," one woman told Newshub. "It was actually horrific."
2:10pm - Most media outlets leave the scene as officials continue to investigate.
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1:55pm - Resident Bill Mclean says the explosion came out of nowhere.
"Basically there was just this almighty bang," he told Newshub. "When I looked across my lounge the sliding doors were moving in and out."
1:40pm - Emergency services remain at the scene. There's no word as yet when cordons might be lifted.
1:25pm - Newshub reporter Heather McCarron says a "mangled, twisted" wreck is all that remains at the house of the centre of the explosion.
"The roof and cladding have been completely blasted off," she says. "Leaving behind a mess of exposed, buckled framing and wires.
"Across the road, garage doors are bent, doors are shattered."
She says the street was covered with debris.
"It's no wonder this blast was heard from kilometres away."
1:10pm - FENZ area commander Dave Stackhouse says they are lucky not have any fatalities from the explosion.
"The condition of the patients is a concern to us and we'll monitor it as we go," he said at a media briefing.
1:05pm - Newshub reporter Dave Goosselink was at the scene and shared dramatic images of the aftermath.
12:55pm - A group of men who were near the explosion when it happened have described to Newshub what the scene was like when they arrived.
Liam Wehi-Hayes, James Looyer and Jack Braithwaite were among the first to arrive.
"We ended up getting in the van, it was all about a hundred metres up the road, by the time we got there there were people out on the street and everything," Wehi-Hayes said.
"We ended up heading up the driveway opposite to the actual property, peaked our head over the fence and we actually saw bodies, debris, the fire was already started and yeah pretty much just dismay everywhere.
"It was quite shocking when we first saw it, instincts kicked in, we all jumped over and tried to help as best we could. It was all pretty shocking but everyone there was helping it was really good."
The group told Newshub they dug shocked victims out of the rubble.
"We just had a look at that fence and saw people underneath all the rubble and everything," Looyer said.
12:45pm - Police continue to advise people to avoid the area, and follow diversions which are in place.
12:43pm - FENZ confirms the fire in the house which exploded has now been extinguished.
"A fire investigator is on the scene," a statement said. "Five properties have been severely affected by fire and one has been destroyed.
"A further 17 properties have been impacted by debris."
12:30pm - WorkSafe confirms it has been advised of the incident, and is making inquiries.
"We can provide no further information at this stage," a statement said.
12:20pm - Preschools in the area - Owls Nest and BestStart - are still running as normal, it has been confirmed.
11:55am - James Looyer, a carpet layer who was working down the road at the time, told Newshub he ran down the street following the explosion.
"It just sounded like some sort of bomb," he said. "We all came running out of the house were working in and stood on the road.
"We thought it was an earthquake to begin with."
11:42am - Harewood councillor Aaron Keown was at the scene. He says anyone worried or needing support should head to the Styx Mill Country Club.
11:40am - Newshub reporter Dave Goosselink says power has been turned off in the wider Styx Mill Country Club community.
11:30am - Fire and Emergency New Zealand area commander Dave Stackhouse, St John territory manager Craig Dowling, and Senior Sergeant Kerry Gray, of Christchurch, confirmed in a media briefing six people had been injured. Their statuses ranged between critical and serious.
The explosion was caused by gas, it has been confirmed.
Emergency services are working to assess the damage, and looking for other gas leaks.
There has been significant damage to properties, with about five affected.
11:15am - Newshub reporter Erin Speedy said lots of houses have been evacuated.
She said residents have been told to turn their gas off.
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11:10am - A man near the scene told Newshub his 16-year-old son was still inside the cordon. He said damage had been caused to their house.
"It's busted in all the ranchslider doors and windows and ripped them off the house.
"It looks like the house if fairly close to ours."
10:30am - A FENZ spokesperson told Newshub it was called to the incident on Marble Ct about 10:15am.
The spokesperson said four fire appliances and a command unit were in attendance.
Initial reports suggested a number of people were injured and a house was on fire, a police statement said.
One man near the scene told Newshub he and his wife heard a big bang and his windows shook, originally thinking it was an earthquake.
Other witnesses reported the explosion blew out the windows of nearby houses.
Twitter posters reported hearing the explosion from as far away as West Melton.