The wreckage of the KA locomotive, the sixth carriage and the rail bridge, in the Whangaehu River at Tangiwai, 25 December 1953.

The Tangiwai disaster is New Zealand's worst rail accident. It occurred at 22:21 on 24 December 1953 when the Whangaehu River bridge collapsed beneath a Wellington to Auckland express passenger train at Tangiwai, in the central North Island of New Zealand. The locomotive and first six carriages derailed into the river, killing 151 people. The subsequent Board of Inquiry found that the accident was caused by the collapse of the tephra dam holding back nearby Mount Ruapehu's crater lake, creating a large lahar in the Whangaehu River, which destroyed one of the bridge piers at Tangiwai only minutes before the train reached the bridge.

• http://en.wikipedia.org/wiki/Tangiwai disaster