In 1976, a giant thunderstorm stalled at the top of the Big Thompson river and dumped an insane amount of rain (7 inches in one hour). It was just too much for the narrow canyon, and the 30 foot wall of water washed everything out. 144 people perished. 5 have never been found. Colorado State Patrol Sgt. Willis Purdy drove into the canyon trying to warn people. His last transmission was "I'm stuck, I'm right in the middle of it, I can't get out..."