The official body count was 450 dead, but the actual number was substantially higher since this area had many transient farm workers who were never counted.
The dam broke just under two years after its completion. More than 900 buildings and $13 million in property ($200 million in today's dollars), were destroyed in the resulting flood. But the greatest tragedy of this disaster was that no one needed to perish.
There was ample warning time before the dam broke as a worker saw some water leaking and informed the engineer who designed the dam and he came out to take a look and didn't see a problem. He of course was wrong and that fateful night a wall of water as high as 140 feet, flowed down the canyon finally making its way into the Pacific Ocean. It traveled 54 miles in 5.5 hours, destroying everything in its path. :(