Updated

A construction manager who joined rescue efforts after New Zealand's devastating earthquake describes rescuers using a hacksaw to cut off a man's leg to free him after he was pinned under concrete.

Fred Haering says rescuers used sledgehammers and chain saws to cut into the collapsed Pyne Gould Guinness building in Christchurch from the roof, slicing downward through layers of sandwiched offices and finding bodies crushed under concrete slabs.

One man had a leg pinned under concrete, and a doctor administered medicine to deaden his pain. A fireman asked Haering for a hacksaw. Haering handed it over and tried to avert his eyes as the man's leg was sawed off, saving him from certain death.

Haering says: "It's a necessity of the game."