Mammoths

Can you site a source stating that hundreds of thousands of mammoths were flash-frozen? I have heard this before, but have been unable to find any reliable evidence for it. Wikipedia's article on mammoths describes frozen remains as being rare, and there are explanations that don't invoke the need for them to have been quick-frozen--an act which would have required them to be reduced to -150°F within minutes! There HAVE been hundreds of thousands of bones and tusks found, but very few complete, frozen carcasses.