A magnitude 6.6 earthquake centred north of Christchurch has jolted New Zealand, sparking a tsunami warning.
The quake, located 20km south east of Hanmer Springs in North Canterbury at a depth of 16km, struck just after midnight on Sunday.
The Ministry of Civil Defence and Emergency Management warned those near the eastern coast on the South Island that a destructive tsunami was possible and advised people to stay out of the water and avoid beaches and shorelines.
People on the coast should move inland and head for higher ground it said.
It said the first wave had arrived in the north eastern coast of the South Island and it may arrive on the eastern coasts of both islands.
It said the first wave may arrive later and may not be the largest and said waves may continue for several hours.
It warned people to expect aftershocks and a host above magnitude 5 were recorded with the biggest a 6.2 shake situated 15km north of Kaikoura.
A St John Ambulance spokesman said it had no reports of injuries from the quake.
It was monitoring the situation but had yet to activate its emergency operations centre.
The police's 111 emergency call service had briefly gone down but was now operational.
Some areas lost power after the quake and there were reports on social media of people on the streets in downtown Wellington after leaving their apartment buildings and there were reports of minor damage.
People in Cheviot, at the epicentre of the first quake are reporting serious damage.
"Family friends in Cheviot say some houses are gone" a woman named Brodie tweeted..
In nearby Hanmer Springs Kylie Richardson reported power outages. "Felt awful and huge here in Hanmer. We're ok," she tweeted.
A woman named Karen reported that Kaikoura, which is still experiencing aftershocks, was "taking a bashing right now".
Kiwis across the country are reporting damage from the more than 22 aftershocks that struck in the hour after the initial tremor.
Other damage reports are coming from Christchurch and Wellington, where power is out in some parts of both cities.
In Wellington cement facades have fallen onto footpaths, water is pouring from a number of underground car parks and windows have been smashed.
Residents have mostly reported minor damage. In one apartment building a large shelf appears to have collapsed onto a bed, while other reports extend to items falling off shelves.
Newshub reported that a chimney had collapsed at the Fiji High Commission in Wellington.
Wellington mayor Justin Lester tweeted that there was some damage in Wellington's CBD.
"Reports are relatively minor to date and we have people assessing now," he said.
In February 2011 a destructive 6.3 earthquake killed 185 people in Canterbury.
