What happened?

It's the 24th of December, Christmas eve, 1953.
Painful news spreads throughout the country; The Wellington-Auckland night express had plunged into the raipidly flooded Whangaehu River at Tangiwai.

A huge lahar had, just minutes before, began to swarm down the river at high speed. The train had no warning of this and was highly unsuspecting as another train had just hours before passed the very same bridge. The train crash was so awful that not only was it the worst in NZ but the 8th worst in the world at the time. The first four carridges were engulfed by the raging torent with no chance of survival. The 5th of the 9 carridges hung precariously on the edge of the broken bridge before dropping into the wild river. Amazingly 21 of the 22 people in this carridge survived. A man named Cyril Ellis had not been able to pass the bridge when he saw the train lights approaching. He attempted to stop the train by flashing a torch. The trains driver had engaged the breaks 200m before the bridge and that is the only reason that 134 people of the 285 survived.