As many as 120 people could be trapped in the rubble of the Canterbury television building in Christchurch. One woman was able to contact her husband on a cellular phone.
At least one man was pulled from that TV building alive, but rescuers had to amputate his leg to save him.
Wednesday, one woman was rescued after being buried under a building for more than 24 hours. Others haven't been so lucky. Rescue crews describe scenes where bodies have been found crushed under slabs of concrete.
Rescue operations at the site have been suspended because of continuing aftershocks that have made what's left of the building even more unstable.
The death toll stands at 92.
The quake struck just before 1 p.m. local time Tuesday, when the city was thronging with workers, tourists and shoppers.
This is the second major earthquake to hit Christchurch in six months. The magnitude-7.1 quake that struck in September was a lot less devastating because it was deeper and centered farther away from Christchurch.
Tuesday's quake originated just three miles from the city center.
Christchurch's water pipes have been badly damaged. The hospitals are inundated and many of the streets have large cracks in them. Experts estimate the quake caused about $12 billion in damage.
Hundreds of troops, police and emergency workers picked gingerly through the ruins, poking heat-seeking cameras into gaps between tumbles of bricks and sending sniffer dogs over concrete slabs.
Police announced their curfew in a cordoned-off area of downtown, saying buildings were at risk of crumbling in the aftershocks still rumbling through the city.
Security was also a factor, with six people being arrested since the quake for burglary and theft, officials said.
Los Angeles County firefighters were on their way to New Zealand to help with the rescue efforts. They took with them some 55,000 pounds of equipment. The 74 firefighters are part of the Urban Search and Rescue Team that was also dispatched to Chile and Haiti after devastating quakes in those countries.
Along with firemen, physicians and structural engineers from Southern California are also on their way to New Zealand.
Teams from Australia, Britain, Japan and elsewhere in Asia are also helping the island nation.
Christchurch's airport reopened Wednesday, and military planes were brought in to fly tourists to other cities.
The Associates Press contributed to this report.