Complex sentence: On June 10 2000 and axle broke on a train at Nelaug, causing that train to derail, fortunately the train was moving slowly so there were no serious injuries, but the trains needed adjustments.
Split into simpler sentences: On June 10 2000 an axle broke on a train at Nelaug, causing it to derail. Fortunately the train was moving slowly so there were no serious injuries, but the trains needed adjustments.