On the evening of 5 July 1923, the Auckland to Wellington express was timetabled to leave Auckland at 7.10 pm but was held for more than four hours. One report said that authorities were forced to await news on rain swollen areas of the Waikato through which the express would pass, and the decisionto go was not made until 10 pm. It also said that the earlier northbound express on the same route had been delayed due to landslips, and cleaning of the carriages had been necessary before it could return to Wellington as the ill-fated southbound express. The express eventually left Auckland at 11.25 pm with about 200 passengers aboard. As the locomotive rounded a curve just south of Ongarue at about 5.52 am the next morning, it struck a landslip caused by heavy rain. Embedded in the landslip was a boulder of about 1.5 metres diameter. This boulder derailed the locomotive and threw it onto the bank of a cutting, causing the first and second carriages to telescope completely. The third carriage was partly telescoped onto the second. The postal van, between the locomotive and first carriage, was almost undamaged and none of its three postal workers was injured. About four chains of track were torn up. Mr A. Stewart, the driver, said that he had shut off steam at the top of a rise and the train was proceeding downhill under its own weight. As it rounded a sharp bend he got a glimpse of the slip and the engine was ploughing through it before he could apply brakes. He thought the train could have cleared the slip safely but for the "huge boulder", which was carried along for two or three chains before the engine derailed. Stewart suffered a badly scalded arm and bruises on the head and thigh. Campbell, the fireman aged 27, was badly scalded and suffered cuts to his nose and an ear. The train's guard, H.P. Hobson, stated in an interview that the train cleared Ongarue and was then running about 25 to 30 miles per hour. About a minute and a half later, he said, the train came to a sudden stop. Hobson sent the sleeping-car attendant back along the track to Ongarue to raise the alarm. A relief train from Taumarunui arrived within two hours after the disaster carrying rail workers and equipment. Hobson confirmed that the presence of the boulder in the slip was primarily responsible for the telescoping of the second-class carriages in which all the casualties occurred. He described in detail the circumstances of the wreckage and injured, and said that the first of the injured were sent to Taumarunui within two or three hours after the disaster, with the remainder arriving there shortly after noon.
Casualties
Eleven passengers were killed outright, and another two died either en route to Taumarunui Hospital or shortly after arrival there. Four others subsequently died.
Inquiry
The three-man inquiry released its report on 30 August 1923. The inquiry heard evidence from 51 witnesses and found that there were good grounds for concluding that the slip was falling as the train approached, and that boulders obstructing the track were the cause of the disaster. No railway official was found guilty of neglect.
