The train comprised carriages containing 600 people and several wagons loaded with South African cement. The carriages were uncoupled about 5 km from Tenga, possibly as part of a manoeuvre by the train crew. The carriages then rolled down the line into Tenga, and crashed into the stationary rail wagons loaded with cement from the train which were coupled to the locomotive.
The crash was blamed on human error and a manoeuvre that went wrong. It appears that the crew were intending to go back and pick up the carriages. The worst casualties were in the first two carriages. Hence it appears that the carriages crashed into part of the same train, not a following train.