On 6 November 1920 nine people were killed after a private mill train ran out of control down a steep gradient. The 32 wagon trail loaded with sleepers departed the Mornington Timber Mill en route for Wokalup 10 km away where it would then travel to Perth or Bunbury. The train was estimated to weigh 600 tonnes and only three wagons had vacuum brakes.

The line to Wokalup was almost all downhill and shortly into the journey the train started to gather speed at an alarming rate. The train left the line on a sharp 'S' bend. Most of the 32 wagons were derailed with some lying on their side. Seven mill workers, the driver and fireman died.