Residents of Christchurch suffered a horrible sense of dé ja vu as two powerful earthquakes hit the city just four months after a powerful tremor killed 181.
Panicked people ran into the streets fearing a repeat of the February disaster, as the magnitude 6 earthquake shook the ground and caused more buildings to collapse.
The first shake was then followed by another tremor of 6.5 magnitude, and a series of terrifying aftershocks.
There has so far been no deaths reported, but at least 10 people are thought to have been injured.
First reports said buildings had been damaged, power had been cut off and roads split open.
Canterbury Earthquake Recovery Authority chief executive Roger Sutton says it's unclear at this stage how many more buildings have been damaged, but guesses around 50.
He told nzherald.co.nz: 'More buildings have been seriously compromised by this. I'm guessing there's maybe another 50 buildings that will have to come down as a result of this. The Grand Chancellor is on more of a lean. We had surveyors in there when the second shake happened.'
Mr Sutton says the CBD is likely to remain closed for at least the next 24 hours.
Christchurch was still trying to recover from the devastating 22 February earthquake which killed 181 people. There had also been an earlier damaging earthquake of 7.1 magnitude five months earlier.
At Canterbury University, items were thrown from shelves and floors were littered with broken glass.
Other parts of the city reported fires breaking out and liquefaction - with the ground bubbling with under-surface sand.
Rocks as large as car wheels came rolling down a hill, narrowly missing vehicles below.
Aaron Gilmore, an MP living in the east of the city, described how the quake hit as he was getting out of his car.
'I could see the ground rise on the road - it was a bit freaky,' he said.
'The wall of my office is cracked and I'm trying to find out what damage has been caused in other parts of the area.'
An aftershock which hit the city was described by city council staff as 'very, very significant' , confirming that a number of buildings had collapsed in the red zone, established after the February earthquake.
Emergency teams from the civil defence headquarters said the Hotel Grand Chancellor, feared on the point of collapse after the February quake, had tipped further over.
The Art Centre's historic clock tower had lost its clockface, narrowly missing the Art Centre's director Ken Franklin.
'I saw stuff coming down off the front of the clock tower, he said.
'It was a very uncomfortable place to be because I was trapped between the clock tower and the fence.'
And more masonry has also fallen from the Christchurch Cathedral.
See footage of the quake below: