Civil Defence has declared a state of emergency in Christchurch following a massive earthquake in the city early this morning.
The magnitude 7.1 earthquake struck about 41km west of Christchurch at 4.35am today, at a depth of 10km, causing injuries, structural damage and gas leaks, cutting power, and rupturing water and sewerage mains.
Roads are blocked by debris, some in the central city caused by building frontages of older buildings collapsing.
Cars have been crushed under the rubble, and wardens are warning people to stay away from older buildings as they fear further collapses.
Christchurch Hospital spokeswoman Michele Hider said a number of people had received minor injuries but two - both men in their 50s - were more seriously injured.
One was hit by a falling chimney and was in a serious condition in intensive care, while a second received serious injuries after being cut by glass.
Civil Defence Minister John Carter rushed to Wellington, where the National Crisis Management Centre in the Beehive has been activated to monitor the quake, and co-ordinate central government response.
He announced a state of emergency had been declared about 10am, and said it would give Civil Defence officials more power.
Carter, Prime Minister John Key and Energy Minister Gerry Brownlee would fly to Christchurch aboard an airforce plane, arriving about 2pm.
The United Nations had contacted the gvernment and was being kept informed of the situation, which Carter described as a "significant disaster".
"Stay calm," was Carter's message to Christchurch residents.
"I know it's a difficult thing and people are in shock, and that's understandable.
"It's a pretty horrible situation."
Carter said many people were suffering from shock but he urged the public not to flood the hospital with minor injuries. They should instead go to their local 24-hour medical centres.
"The most important thing we can tell anybody at the moment is please don't panic," he said.
"Be safe, make sure your friends and family are safe."
The army had been informed and was ready to mobilise if needed, and all systems were operating as they should in an emergency, Carter said.
Brownlee, who is MP for Ilam, said he expected power to be restored this afternoon.
Police are advising people to stay out of Christchurch city and have shut down the CBD.
Detective inspector Malcolm Johnston told ONE News that they have been assesing the damage.
"Older buildings have sustained more damage than the newer ones and we have some safety issues."
He said aftershocks were concerning and that the police station has been rocking since the initial quake hit.
One of the biggest, at magnitude 5.2, came just minutes before 8am, making it about a dozen aftershocks in total.
"Stay inside and stay safe," he said.
Inspector Mike Coleman said police had cordoned off central Christchurch as it was dangerous but also because looters had already been active.
"There's considerable damage there, and we've already had reports of looting," he told Radio New Zealand.
"Shop windows are broken and obviously it's easy pickings for displays and things."
Police had taken about 300 calls in the first couple of hours following the quake, with many people concerned for relatives.
"We're telling people to check their neighbours...and obviously to go to their Civil Defence centre if they feel unsafe in their houses," Coleman said.
"Stay off the roads and also avoid the central city. We've got considerable road damage, there's gas leaks, there's been damaged water pipes, we've got sewage in houses and quite a lot of power lines and power poles down. It's very unsafe to be out and about."
Transport Agency operations manager Pete Connors says State Highway 77 between Ashburton and Darfield is closed south of Glentunnel and south of the gorge bridge.
Dyers Road around the city is also closed at State Highway 74.
Connors also said that a number of roads close to the city have moved so people should drive with care and if they don't need to travel, they shouldn't.
Power is out from Rakaia, 60km southwest of Christchurch, to the Waimakariri River, north of the city.
Orion chief executive Roger Sutton said power was also off across the Canterbury Plains, through to the foothills of the southern alps.
However power will back back on for 90% of Christchurch city by 6pm.
Hospitals flat out
All Christchurch Hospitals are operational, though people were asked to go to hospital only if it was an emergency.
For minor injuries, residents could go to the 24-hour surgery on Bealey Avenue, and the Riccarton and Moorhouse after hours medical centres were open.
Canterbury civil defence emergency duty officer Andrew Howe said people who had evacuated their homes have gone to their local sector posts.
He said engineers were still assessing the infrastructure damage in the region.
Christchurch Airport was reopened at 1.30pm after being assessed following concerns for the integrity of the runway.
For more information visit the Civil Defence Website.
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