The railway line between Inverness and Perth has been closed today after a train derailed during testing overnight.
It happened close to Dalwhinnie station in the Highlands around 3.15am.
Scotrail said it was not a passenger service and no one was injured.
Recovery crews remain at the scene but it is not known how long it will take for the line to reopen.
Services have been disrupted in the meantime. Trains heading north are only able to go as far as Pitlochry and will restart at Aviemore.
NEW: Due to an overnight issue at Dalwhinnie, we're currently unable to run services between Perth and Inverness, in both directions.
The following service alterations will apply until further notice: pic.twitter.com/bMTaWbQzMT
— ScotRail (@ScotRail) April 10, 2021
Southbound trains are stopping at Aviemore and starting again at Pitlochry.
Replacement buses are running in their place.
The Rail Accident Investigation Branch released a statement earlier saying it was looking into the incident.
The agency said: “We are deploying inspectors to gather evidence following the derailment of a test train at Dalwhinnie on the Highland Line in Scotland.
“The train consisted of a short-form HST that was travelling south when the last two vehicles derailed in proximity to points.”