After the news that three people had died in the train derailment, Scotland's First Minister Nicola Sturgeon tweeted: "My deepest condolences are with the loved ones of those who lost their lives in this tragic incident.

"I have just been updated by Network Rail and the emergency services on the ongoing operation. My thanks go to them, and my thoughts remain with everyone affected."

Three people, including the driver, have been pronounced dead at the scene of the train derailment in Stonehaven, in Aberdeenshire, and six people have been taken to hospital, British Transport Police said.

What else do we know:

• The train was travelling from Aberdeen to Glasgow and derailed at Carmont near Stonehaven at 9.40am
• A major incident was declared and about 30 emergency service vehicles - including air ambulance support - were been called to the scene.
• Smoke was seen coming from the area, where landslips have been reported.
• The passenger train was made up of two locomotive power cars and four carriages.
• It is understood a locomotive and three carriages derailed and slid down an embankment

British Transport Police said three people were pronounced dead at the scene of the Stonehaven rail crash.

They said: "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."

Six people have been taken to hospital to be treated for injuries, which 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 under way.

"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.”

Three people, including the driver, have been pronounced dead at the scene of the train derailment in Stonehaven, in Aberdeenshire, and six people have been taken to hospital, British Transport Police said.

The Scottish Conservative leader Douglas Ross has described events in Stonehaven as "heartbreaking and hard to bear."

The MP for Moray said all his thoughts were with the family and friends of those involved in the derailment, and he thanked the emergency services for their bravery in dealing with the incident.

BBC News Channel

Grant Shapps told the BBC News Channel it was a "very serious incident" and that he was still waiting for a clearer picture of the numbers of people involved and details of casualties.

He said staff from the Rail Accident Investigation Branch were leaving Farnborough in Derby this afternoon to travel to the scene.

He added that rail workers were working on an unrelated project not too far from the scene and had been able to help.

He acknowledged there had been some very extreme weather and concern about landslips.

Image source, Network Rail

The railway line between Aberdeen and Dundee was upgraded in a £9m Network Rail project last year.

Over six weekends in February and March, engineers renewed 2,500m of track at a number of locations along the line between the two cities.

This included improvements to the level crossing at Carmont, near where the passenger train derailed.

The project involved installing a total of 3,500 new concrete sleepers and 2,500m of rail.

Tom Burridge
Transport correspondent

Early indications are that the heavy rain could have been the main factor in causing today’s crash in Aberdeenshire.

One rail industry source says the 0638 service from Aberdeen to Glasgow was initially halted because of flooding on the line.

The driver apparently contacted control to ask permission to switch tracks.

It’s believed the train reversed and switched to clearer tracks and then continued on its route to Glasgow.

Then it is thought the train hit a landslide and derailed.

However this initial, unconfirmed version of events should now be closely examined by the UK’s Rail Accident Investigation Branch.

Its job is to establish all the facts.

The train’s computer systems should show key indicators like the speed it was travelling at when it left the track.

In recent years incidents like this on the UK’s railways have become incredibly rare.

The last major derailment was in 2007 in Cumbria.

Network Rail had tweeted that there were reports of a landslip at Carmont just minutes after transport police were first alerted to the derailment.

The video attached to the tweet shows the line was badly flooded close to where the train derailed

Coastguard teams from Aberdeenshire, Angus and Ayrshire have been assisting at the scene of the derailment.

The HM Coastguard was alerted at about 10:30 and rescue teams were sent from Aberdeen, Stonehaven, Cruden Bay, Banff and Montrose.

A search and rescue helicopter based at Prestwick, Ayrishire, also flew to the scene.

The coastguard said the personnel were part of a "multi-agency response".

A spokeswoman said: "Two coastal operations area commanders and four senior coastal operations officers are also at the scene."

The World at One
BBC Radio 4

Train expert Tony Miles told the World at One that the weather conditions were believed to have been responsible.

"The embankments get so saturated they can't hold themselves together structurally any more and collapse.

"I'm guessing the driver would have been driving cautiously but it takes quite a while to bring a train to a halt and even if you did spot something on the track it would have been too difficult to bring the train to a halt."

Local MP Andrew Bowie had been in Stonehaven surveying flood damage earlier on Wednesday as news of the derailment was breaking.

The River Carron, the main river which flows through it, had burst its banks, causing flooding in the town centre and side streets.

Image source, Martin Anderson/PA Media

"Luckily, the water receded incredibly quickly and the river has peaked and is going down," he said.

"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."

Mr Bowie siad he had spoken to the UK Transport Secretary Grant Shapps, who is liaising with Network Rail Scotland and ScotRail about the derailment.

The World at One
BBC Radio 4

Tony Miles writes for Modern Railway magazine.

He told the World at One: "The train involved was the 6.38 from Aberdeen to Glasgow and it called at Stonehaven as normal.

"It carried on through Carmont, where the driver spotted a landslip. So he was advised, it appears, to take the train back to Stonehaven so passengers could be taken off.

"It appears the train hit a second landslip on its way back to Stonehaven.

"It's a six-vehicle train - two power cars and four coaches and it appears five of them have derailed some seriously.

"It really is serious and there have been casualties."

Local MSP Mairi Gougeon said Network Rail had been unable to tell her how many people were on the train or how many were injured.

Image source, Martin Anderson/PA Media

She said: "We did have exceptionally heavy rain here last light.

"The town of Stonehaven has seen flooding earlier this morning because of that heavy rain. I believe from Network Rail that they may initially believe that may be a cause of what's happened here today.

"My thoughts are with everyone involved with the tragic accident".

Yesterday's heavy downpour has caused major flooding issues in Aberdeen and Aberdeenshire.

Many schools were unable to open this morning because of safety concerns over the weather.

Stonehaven was badly affected by the storm. One business said it was their fourth flood in nine years.