Christchurch Mayor Bob Parker says 55 bodies have been identified after Tuesday's massive earthquake.
With 20 other deaths confirmed, though the bodies have yet to be recovered, the official death toll is now 75.
There are also 300 people believed to be missing but details are unclear and officials are currrently trying to refine that list.
The Prime Minister has declared a national state of emergency.
New Civil Defence information released on Wednesday morning shows that 22 people are missing at Christchurch Cathedral, with more than 20 fatalities expected at that location alone.
Civil Defence says seven people have died in the Canterbury TV building and more than 22 are still missing there.
Twenty-four have been rescued from the Pyne Gould building and dogs have detected another seven still alive.
No sign of life has been detected, however, by dogs at the Smith City carpark.
Hundreds of search and rescue personnel, fire service staff, army personnel and volunteers worked under floodlights through the night and morning to get to those who are still trapped - some of whom have been texting for help.
The chief executive of the Canterbury Chamber of Commerce, Peter Townsend, says this is the nightmare that didn't happen in September, when the 7.1 quake caused extensive damage but didn't kill anyone.
The fire service's head of special operations, Jim Stewart-Black, says more than 200 search and rescue personnel are on the ground, with more overseas teams due to arrive later on Wednesday afternoon.
Christchurch Mayor Bob Parker says the central city will be shut down on Wednesday and will stay that way for a significant amount of time.
Mr Parker says a cordon manned by military personnel is in place around the four avenues surrounding the central area, and there's no way it will be lifted in the immediate future.
Civil Defence is urging sightseers to stay out of the central city, as they are slowing down emergency vehicles, particularly at intersections.
It says the central city needs to remain as clear as possible for those helping with the rescue effort.
