Christchurch quake survivors described yesterday how they dodged concrete blocks and sheltered under desks, waiting terrified in the dark for rescuers to arrive.

But amid the tales of bravery and miraculous escapes, there was also tragedy as residents told how they saw people killed by falling debris and writhing in agony from serious injuries in the wake of Tuesday’s 6.3 magnitude tremor.

Advertising executive Sven Baker said a snap decision to dive under his desk, rather than rush onto the street, saved his life as the top two floors of his building tumbled onto the road.

“It was a miracle to have walked out,” he said. “It was a massive earthquake, just unbelievable (it) took you off your feet and the aftermath was just mass destruction.

“The split-second decision was to run out into the street or dive under a car or under the table. I went under a table just as the whole façade of the building collapsed on the street, so I’m pretty grateful for that instinctive decision.”

Mr Baker said the streets were crammed with panicked people.

“It was just like a battle zone, just a street full of dust and screaming people and the smell of gas,” he told the New Zealand Herald.

Paul Hewitson said a concrete slab was bearing down on him and two colleagues taking lunch in their office but they survived being crushed because of the way it happened to fall.

“We got into the doorway of an office and suddenly it was like a bomb went off and a concrete slab above my head came down... I had a cellphone with me and was trying to call out. We didn’t know what was happening,” he said.

“The concrete slab fell at an angle, it didn’t fall completely flat, so that’s primarily what saved us,” he told Radio New Zealand.

The force of the quake tossed Anthony Rohan around like a rag doll before he took shelter under his desk.

“Bookshelves and files were going everywhere, it was just chaos,” he told Fairfax Media.

“The force of the earthquake just literally threw you around. Trying to get under desks was a mission... you could see the ground move and the buildings flex.”

Others were less fortunate. Tom Brittenden said he saw a woman die with her baby in her arms when she was hit by falling debris in the city’s Cashel Street Mall.

He said the woman appeared to have run from a shop in panic when the quake hit. Her baby survived but she was killed instantly.

“We tried to pull these big bricks off (her)... she was gone,” he told the Christchurch Press.

Mr Brittenden also had grave fears for a man he helped pull from the rubble who was left in agony after falling from a three- storey building.

“We just went in and pulled the debris off some of the people who were in there and pulled them out,” he said.

“We carried one man outside who had fallen three storeys from the top of the building, he had serious injuries, a broken pelvis.”