The crash is thought to be the first incident involving a fatality on a train since a Glasgow-bound Virgin Trains express derailed in Cumbria in 2007, in which one passenger died.
Today’s incident happened after an Inter7City train from Aberdeen to Glasgow had turned back after encountering a landslide, and then reportedly hit another one.
British Transport Police (BTP) said it was called to the line at 9:43am this morning (12 August following a report that a train travelling from Aberdeen to Glasgow Queen Street had derailed.
A spokesperson said: “Very sadly despite the best efforts of paramedics, we can confirm that three people have been pronounced dead at the scene.
“While formal identification is yet to take place, the driver of the train is very sadly believed to have died.
"His family have been informed and are being supported by specially trained family liaison officers.
“Officers are continuing to work to inform the families of the other two people who sadly died.
“Six people have been taken to hospital to be treated for injuries, which thankfully are not believed to be serious.
Chief Superintendent Eddie Wylie said: “This is a tragic incident and first and foremost our thoughts are with the families and friends of those who have very sadly died this morning.
“We remain on scene alongside our emergency service colleagues, and a major incident operation has been underway.
"I would like to reassure the public that this was not a busy service, and from CCTV enquiries and witness statements we believe all passengers have been accounted for.
"However, once the area has been made safe then a full and thorough search will be conducted, which is likely to take some time.
“I know many people will understandably have questions, and we will be working closely alongside the Rail Accident Investigation Branch and the Office of Rail and Road to establish the full circumstances of how the train came to derail.”
‘Extremely serious incident’
Earlier, First Minister Nicola Sturgeon told MSPs a major incident had been declared.
She described the derailment as an “extremely serious incident west of Stonehaven”.
The Transport Salaried Staffs Association (TSSA) union said four carriages of the 6:38am Aberdeen to Glasgow Queen Street service had derailed.
The union, which represents engineering and maintenance staff at Network Rail and ScotRail, said the incident happened at Carmont and was reported around 9:45am.
It said the derailment had followed a night of thunderstorms and heavy rainfall.
General secretary Manuel Cortes said: “Our thoughts are with those caught up in this derailment, their loved ones and the emergency services and our members who are now involved in a rescue operation.
“Our union has had concerns about the amount of hours that some of our members who maintain have been doing.
‘Our thoughts are with everyone involved’
"However, it's far too early to speculate whether this may have been a contributing factor to this morning's incident.”
Kevin Lindsay, organiser in Scotland for the Aslef train drivers’ union, said: “At this time our thoughts are with everyone involved in this incident.
"We are aware it is an extremely serious incident and our thoughts are with everyone involved.”
Rail journalist Phil Haigh tweeted: “Train derailed was 0638 Aberdeen-Glasgow.
"It stopped south of Carmont having seen a landslip.
"It was returning north, initially on the southbound line, then on the northbound having crossed at Carmont.
"It then hit a second landslip and derailed as it was returning to Stonehaven.”
Rail Maritime and Transport union senior assistant general secretary Mick Lynch said: “RMT is aware of the major incident at Stonehaven and our reps are liaising directly at senior level with both ScotRail and Network Rail.
“Our priority at this time is to support our members, their colleagues and their families and to do all that we can to assist the rescue operation which RMT members are currently involved in.
“The facts behind this incident will need to be established in due course but at this stage we are focussed on support and assistance and our thoughts are with all those impacted by this tragedy.”
Scottish Conservative leader Douglas Ross said: “Today's events are heartbreaking and hard to bear.
“Only one conclusion can be drawn from the early reports and images we have seen - this is nothing short of a disaster.
“All our thoughts are with the family and friends of those involved, and I would like to thank the brave emergency services who are dealing with the incident.”
British Transport Police tweeted: “We're currently responding to an incident on the line in Stonehaven, Aberdeenshire, where a train has derailed.
“Officers were called to the scene at 9:43am and remain there alongside paramedics and the fire brigade.
A ScotRail spokesman said: “We’re assisting the emergency services with an incident near Stonehaven, and will provide more information when available.”
Network Rail Scotland, which owns the tracks, tweeted: “We are working alongside the emergency services to respond to an incident involving a train near Stonehaven.
"It is too early to confirm the exact nature and severity of the incident and more details will be made available once known.”
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