Three people are believed to have died after a train derailed in Aberdeenshire amid heavy rain and flooding.
One person is said to be still missing, rail industry sources told the PA news agency, after the ScotRail service crashed near Stonehaven on Wednesday morning.
The sources told PA the suspected cause of the incident is a landslip.
They said the train stopped due to a landslip and moved back along the line when it crashed into another landslip.
The train involved was the 06.38 Aberdeen to Stonehaven, made up of a locomotive and four carriages.
It is understood the locomotive and three carriages derailed and slid down an embankment.
Dozens of emergency service vehicles, including an air ambulance, were called to the scene at around 9.40am.
Unions called the crash a “tragedy” as a major incident was declared at Aberdeen Royal Infirmary.
Industry sources have told PA three people, including the driver, have died, although that has yet to be officially confirmed, and one person remains missing.
The sources said there were 12 people on the train – six passengers and six staff.
Speaking before First Minister’s Questions on Thursday, Nicola Sturgeon said although “details are still emerging”, there are “early reports of serious injuries”.
She said: “My immediate thoughts and the thoughts of those across the chamber are with all those involved.”
She later tweeted the NHS Grampian helpline number: “Anyone worried about friends or family involved in the Stonehaven rail incident can call 01224 319519 for advice and support.”
The First Minister is holding a Scottish Government resilience meeting on Wednesday afternoon.
Local MP Andrew Bowie said he had spoken to the UK’s Transport Secretary Grant Shapps, who is liaising with Network Rail Scotland and ScotRail about the derailment.
He told PA: “It’s obviously a terrible situation, a train derailment, the emergency services are on the scene.
“I’ve already spoken to Grant Shapps, who has spoken to Network Rail and the British Transport Police, who are obviously investigating and assisting.
“I am aware that Aberdeen Royal Infirmary has declared a major incident.”
Prime Minister Boris Johnson tweeted: “I am saddened to learn of the very serious incident in Aberdeenshire and my thoughts are with all of those affected. My thanks to the emergency services at the scene.”
Train operator ScotRail posted a message on Twitter shortly after 6.30am warning that services across Scotland would be disrupted due to “extremely” heavy rain and flooding.
Video posted to social media by Network Rail Scotland showed a landslip on the track at Carmont, believed to be close to the scene of the crash.
It is unclear whether the landslip was directly related to the derailment.
Network Rail tweeted at 9.49am: “At Carmont, we’ve had reports of a landslip, which means services can’t operate between Dundee & Aberdeen.”
Police had said reports of the train derailment were first received at 9.40am.
NHS Grampian has set up a “welcome centre” at Midstocket Church in Aberdeen for those impacted by the crash, staffed by the health board’s chaplains.
Mr Bowie had been in Stonehaven surveying flood damage earlier on Wednesday.
He said: “The situation was really bad this morning, the River Carron, the main river which flows through it, had burst its banks and the heavy rain had caused flooding in the centre of Stonehaven and lots of the side streets leading off it.
“Luckily, the water receded incredibly quickly and the river has peaked and is going down.
“Obviously none of us expected there to be such a serious incident as a rail derailment at the same time, but it just goes to show how damaging the bad weather can be.”
He added: “I don’t think speculation is helpful at this stage.
“We obviously don’t know why the derailment took place but obviously we have suffered terrible weather here.”
Mick Lynch, the assistant general secretary of the Rail, Maritime and Transport union said: “The facts behind this incident will need to be established in due course but at this stage we are focused on support and assistance and our thoughts are with all those impacted by this tragedy.”
Paul Plummer, chief executive of the Rail Delivery Group, which represents the rail industry, said: “We are saddened to learn about the incident in Aberdeenshire today and our thoughts are with those affected.
“While an investigation will follow, our current focus is to provide every support we can in the immediate response.”
The last time a train driver was killed in a crash on Britain’s railways was in Berkshire in November 2004, the Office of Rail and Road said.
Seven people died when a train collided with a car that had been deliberately driven onto a level crossing at Ufton Nervet.