Police believe it is unlikely any earthquake survivors will be found in the collapsed Canterbury Television building. About 100 people are believed to be inside.
The building in central Christchurch is one of many severely damaged after the 6.3-magnitude quake struck at 12.51pm on Tuesday, killing at least 75 people and causing widespread destruction.
Police on Wednesday said they were preparing for the recovery phase.
Police say an urban search and rescue team believes it would not be possible for people to survive in the fire-blackened ruins. Rescuers now need to need to concentrate their resources elsewhere in areas where survivors are more likely to be found.
However on Wednesday evening another search and rescue team arrived at the Canterbury Television building, boosting the number there to about 15.
The building it lit up with floodlights and a tow truck has arrived to pull away damaged cars.
Superintendent Dave Cliff says there are a number of estimates of how many people remain inside the building, ranging from 80 to more than 100.
Operation commander Inspector Dave Lawrie sent his condolences to all families of people trapped inside building, many of whom were from overseas.
A number of Japanese students are believed to have been at an English-language school on the third floor.
Previously, it was reported that 15 people had been rescued, but this was later found to be incorrect.
Police say there has been no sign of life from underneath the rubble of the Cathedral, where about 22 people are thought to be trapped.
A curfew will be imposed in the central business district from 6.30pm on Wednesay until 6.30am on Thursday to protect the public from any buildings which may collapse.
Work continues at Pyne Gould site
Efforts to find quake survivors are continuing at the destroyed Pyne Gould building, where rescuers say they have reason to believe people are still alive.
Police are still trying to confirm the numbers trapped in what was a four-storey building, but hopes of finding survivors are fading on Wednesday night.
Urban search and rescue taskforce leader Paul Burns said on Wednesday night that there had been no signs of life from the building for several hours.
He says rescue teams will work through the night to see whether they can find more survivors, and even though hope is fading they are not giving up.
Rescuers spoke to a woman trapped in the building who spent Tuesday night under a chair and doesn't appear to have been injured.
Overnight on Tuesday, 48 people were pulled alive from quake-smashed buildings - including a baby in the arms of its mother, who had been hit by rubble.
Another person was rescued from the Pyne Gould building on Wednesday morning.
Hotel Grand Chancellor at risk
The Hotel Grand Chancellor is said to be at significant risk of collapse and has been evacuated.
Structural engineer Jade Kirk believes the building has been irreparably damaged. The hotel was displaced by half a metre in the quake and has dropped by 1 metre on one side.
Mr Kirk says the damage to the building is clearly visible and if the building falls, it could bring others down with it.
A two-block radius has been cleared around the hotel.
No-fly zone so rescuers can hear better
Superintendent Russell Gibson says hundreds of rescue workers are going from building to building, systematically checking for survivors, focusing on places they are getting texts and tapping noises from.
Civil Defence has imposed a no-fly zone over the city centre so that any cries or noises can be heard more readily.
Superintendent Gibson says they are having to ignore trapped dead bodies in order to focus on buildings from which noises have been heard.
He says some people have escaped with barely a scratch, while limbs have had to be amputated from others in order to free them.