At least 65 people were confirmed dead and many more fatalities feared after a 6.3-magnitude earthquake hit Christchurch on Tuesday in New Zealand's South Island, causing widespread destruction, DPA reported.
Prime Minister John Key said at least 65 people were dead with many more people yet to be rescued.
Hundreds more have suffered a wide range of injuries.
"We could be facing New Zealand's darkest hour," Key said after arriving in the devastated area following an emergency meeting of cabinet ministers.
Rescue teams were dealing with widespread destruction, including two buses crushed by falling debris.
There were other reports of bodies being pulled out of buildings and crushed cars.
Police said emergency services were battling a number of fires and power was out in many areas.
Members of the public have posted videos of destruction including buildings and cars being crushed in rock slides in suburbs including Sumner and Lyttelton.
Aftershocks were still being felt as buildings were evacuated and people fled the central city area.
Officials asked people to stay off roads as emergency services and the military struggled to get to areas where people could be trapped.
Witnesses said the ground lifted up to 1 metre in places.
The New Zealand Institute of Geological and Nuclear Sciences said the epicentre was near Christchurch, at a depth of 5 kilometres.
The quake, which struck at 12:51 pm (2351 GMT Monday), will have caused more damage than a 7.1-magnitude earthquake on September 4 because of its shallow depth, the institute said.
The September quake, with an epicentre 30 kilometres west of the city at a depth of 33 kilometres, struck in the early morning when city centre was largely empty. There were no fatalities last year.
Tuesday's quake brought down power lines, ruptured pipes and forced the closure and evacuation of many buildings including the airport and university, and disrupted phone communications.