Seven kilometres to the west of Waiouru is the small settlement of Tangiwai, the site of New Zealand's worst railway disaster. On 24 December 1953 the overnight express from Wellington to Auckland passed over Tangiwai railway bridge just after it had been weakened by a lahar from Mount Ruapehu. The bridge collapsed, sending the train into the Whangaehu River, killing 151 people. Many army and naval personnel were involved in the rescue of survivors and the recovery of bodies. Sister Mortimer of the Waiouru Camp Hospital, The Angel of Tangiwai, worked non-stop for three days tending the survivors and laying out the bodies.