Efforts to rescue earthquake survivors trapped in Christchurch buildings are focusing on the Pyne Gould building, where rescuers say they have reason to believe people are still alive.
The shallow 6.3-magnitude quake struck at 12.51pm on Tuesday, 10km south-east of the central city, causing many deaths and widespread devastation.
Fire Service national commander Mike Hall says rescue teams have identified that four to five people are alive in the rubble.
Mr Hall says the people are in two different locations inside and rescuers are working on the delicate task of reaching them and bringing them to safety.
From outside that building, Radio New Zealand's reporter says rescuers have been talking to a woman trapped in the building who spent the 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.
Diggers have resumed work at the Canterbury TV building after earlier being stood down when personnel were sent elsewhere.
The Fire Service estimates there are approximately 50 people unaccounted for in the CTV rubble. 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 is not the case.
Hotel Grand Chancellor at risk
A structural engineer says there is a significant risk that one of the tallest buildings, the Hotel Grand Chancellor, could collapse and bring other buildings down with it.
A two-block radius has been cleared around the hotel on Wednesday.
Structural engineer Jade Kirk says the damage to the building is irreparable and will need to be demolished if it does not collapse.
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.
Mr Gibson says 38 bodies are currently in the mortuary and dozens more in the streets, trapped in cars and under rubble.
Radio New Zealand reporter Jessica Maddock says rescuers at the CTV building are working through mangled metal and twisted stairwells to try to get to survivors.
She says the scaffolding used to fix the building after the September quake has fallen away.