Hope is fading that many more survivors will be recovered from the wreckage of central Christchurch, with fears for more than 300 people still missing after Tuesday's 6.3-magnitude earthquake.
The death toll was confirmed at 71, but this number is expected to rise significantly as more bodies are uncovered. Around 120 people have been rescued so far.
John Key, the New Zealand prime minister, said early on Thursday morning that a rescue operation remained under way, despite a growing sense that the chances of anyone being found alive were minimal.
"We do have to brace ourselves that while the official toll is 71 that number will rise today and tomorrow," Key told local television. Police said the number of missing could be much higher than the 300 estimated so far.
Bulldozers moved in on the Canterbury TV building overnight, with hopes of recovering survivors abandoned. As many as 100 people were thought to be inside. Police reported that the sounds emanating from rubble in the city – mobile phone sounds and tapping – had fallen silent by late Tuesday. Ten Japanese language students were among 23 teachers and pupils at a school based inside the building.
"We don't believe this site is now survivable," the police operations commander, Inspector Dave Lawry, told reporters. Efforts would now be shifted to sites where there was more hope, he added.
Kenti Manning, 15, and his sister Lizzy, 18, had been holding an overnight vigil outside the building for their missing mother, Donna, a television presenter.
"My mum is superwoman, she'd do anything," Lizzy told stuff.co.nz. Soon afterwards, the website reported, a police official bent down beside the pair to say he had "some horrible news" – that their mother could not have survived.
Speaking to the Guardian from her family home near the epicentre of the quake, one resident said few people expected any miracles, nearly two days after the earthquake struck. "It's just too late, too long," she said. "Everyone here knows what is going on – even the kids. Everyone here knows someone who died."
Police have imposed a curfew in the centre of the city, with locals urged to stay at home unless travel is essential. People venturing into the city to view the damage would hamper rescue efforts, said Police Superintendent Dave Cliff.
Hundreds of police, troops and emergency workers using heat-seeking cameras and sniffer dogs were checking the wreckage of buildings toppled by the quake, which caused damage estimated to cost more than £7bn.
The rescue efforts are fraught with danger, with a number of buildings close to collapse, among them a 26-storey hotel.
"If the Hotel Grand Chancellor falls, and three engineers say it is a significant risk, that will be dramatic, a domino effect in the central city of other unstable buildings. It will be a major disaster," Superintendent Cliff said.
There are also large numbers of people hurt in the quake, with Christchurch's main hospital inundated with those suffering head and chest injuries. However, officials said the health system was largely coping, with some patients moved to other cities.
Amid the tragedy there were occasional, brief moments of joy. Rescue workers clapped and cheered as Ann Bodkin was pulled from the remains of the Pyne Gould Guinness building. She had spent a day trapped under her desk.
Christchurch's mayor, Bob Parker, said: "In the midst of what is by and large one of the bleakest days in the story of our city, the sun came out at the same moment as they removed Ann from that building."
Other rescues proved more harrowing, with construction manager Fred Haering describing rescuers using a hacksaw to amputate a trapped man's leg, allowing him to be freed.
Haering told the New Zealand Herald the man had a leg pinned under concrete. A doctor gave him strong painkillers while a fireman asked Haering for a hacksaw to remove the man's leg.
Power remains off for about half the city and water is yet to be restored for large areas, prompting concerns for public health.
Anxiety is high for the hard-hit suburbs of Sumner and Lyttleton, which remain difficult to access. Late on Wednesday police confirmed parts of Sumner were being evacuated.
Roads and pavements are strewn with bricks, cracks, gaping holes and sludge. Traffic lights have almost all failed and army vehicles are parked across intersections.
The airport has reopened for both domestic and international flights. Many foreign nationals have been leaving the temporary camps in which they were accommodated – including tents in Hagley Park, which had been erected to house the annual Ellerslie flower show.
Structural damage and a lack of electricity and water mean few shops or petrol stations in the city can open. Some petrol stations have reported angry clashes among drivers vying to fill up.
A handful of corner shops have kept their doors open despite the restrictions, serving customers in the near-dark.