Another section of railway track in East Sussex has been closed, and weekend train services have been cancelled, after a train derailed on Thursday afternoon
The new closure - between Polegate and Eastbourne - follows a safety inspection. The line between Haywards Heath and Lewes had already been closed following the derailment
It comes after Southern Rail announced cancellations to services between London Victoria and Eastbourne will run into the weekend
Network Rail says it's too early to know what caused Thursday's derailment near Lewes
Two people who sustained serious injuries are not deemed to be in life-threatening condition, police say
Passengers have described the "panic and fear" felt by those on board. "Everyone was screaming," one passenger tells the BBC
Nick Johnson
Reporting from the scene
The Rail Accident Investigation Branch has arrived at the scene, close to the Landport area of Lewes in East Sussex.
It will carry out the the investigation into what happened.
A reminder that Southern says the line will be blocked until the investigation has been concluded.
More now from John Whitehurst, the interim chief executive officer of Greater Thameslink Railway, who says that the investigation will determine the "root cause" of the incident.
Speaking live to BBC Breakfast, he says: "This will be an open investigation with colleagues and Network Rail to learn the causes.
"It is too early to speculate what happened. My first thoughts are with colleagues and passengers."
John Whitehurst, the interim chief executive officer of Greater Thameslink Railway (GTR), which operates Southern services, tells BBC Breakfast that "the railway is very safe".
"These incidents are rare. We do constant safety checks and put speed restrictions in place, or stop trains where necessary.
"We are working with the Rail Accident Investigation Branch and emergency services. The line will be blocked until this has taken place."
Whitehurst says the safety of passengers is the priority.
Image source, Network RailLucy McAuliffe, Network Rail's Sussex route director, says she is “shocked and saddened” by the incident.
“We’re working with the rail accident investigation branch to understand what has happened here, and while that's ongoing, we're working on this complex site to safely recover the railway and reopen for customers as soon as possible,” she adds.
McAuliffe has thanked the local community and emergency responders for their support, and says her thoughts are with those affected.
Image source, Tracy McGregorPassenger Tracy McGregor says the train was full of "brilliant people" who showed "lots of camaraderie" after it left the track.
She was travelling in carriage seven, one of the three which left the track.
She tells the BBC: "People who were in the unaffected carriages walked along the rooves of the three carriages and opened the doors, enabling us to get out.
"The train started swinging after we went over a stretch of track - we were delayed en route so we think the train might have been going quick to make up time."
Nick Johnson
Reporting from the scene
The sun is up in the East Sussex countryside over the site of the derailment.
The railway line sits on a raised embankment in the middle of fields just outside Lewes.
Through the trees I can see the front carriages which remain upright. On the other side of the embankment, the three rear carriages are on their side.
There is still a significant police presence surrounding the embankment and investigators in orange hi-vis jackets are on the track.
Image source, Getty ImagesSouthern Railway has issued advice to passengers hoping to travel in the area today.
Trains are unable to run between Lewes and Haywards Heath, so those travelling to or from Cooksbridge, Plumpton, Hastings or Ore have been told their journey is likely to take longer than usual.
Rail replacement buses are running between Haywards Heath and Lewes, calling at Cooksbridge and Plumpton, and those travelling in the area are being told to allow at least an extra 60 minutes of journey time for their trip.
People travelling towards Eastbourne or Hastings today will also need to change trains at Brighton, with extra carriages being added on services between Brighton and Hastings, and Brighton and Seaford.
Tickets will be accepted at no extra cost on Southern services between Brighton and London Victoria, Thameslink services between Brighton and London Bridge, Gatwick Express services between Brighton and London Victoria, on the London Underground between London terminals, and on Southeastern services between Hastings and London terminals.
Rail tickets will also be accepted on Brighton and Hove Buses’ 28, 29, 29B, and 29X routes, which run between Brighton and Eastbourne, and Brighton and Tunbridge Wells in Kent.
Image source, Eddie MitchellA major incident was declared following a train derailing near Lewes in East Sussex shortly before 16:00 BST yesterday.
Emergency services said about 150 people were on board the train, with two people sustaining serious injuries and a further 18 with less serious injuries. All of the passengers were evacuated from the train.
Photos from the site showed emergency workers around the train on its side in a field next to the tracks, with one passenger saying it "felt like a car crash" and another saying the train derailed from carriage five.
The Rail Accident Investigation Branch (RAIB) deployed a team of inspectors to the site.
Image source, Eddie MitchellGood morning.
An investigation is continuing today into a train derailment near Lewes in East Sussex which left two people seriously injured and 18 others with less serious injuries.
About 150 people were on board the Southern service from London Victoria to Eastbourne when it derailed shortly before 16:00 BST on Thursday.
British Transport Police declared a major incident as three carriages derailed on their side, trapping some passengers on board.
We’ll be bringing you the latest developments.
We're pausing our coverage for tonight.
Thanks for joining us - we'll be back with further developments in the morning.
In the meantime, you can read the full story here.
Goodnight.
Image source, PA MediaPassenger Tracy McGregor was travelling in carriage seven of the train - one of the coaches which left the tracks.
She's told the BBC: "When the carriage left the tracks, it felt like it went on forever.
"I took the brace position, I was preparing to die.
"When the train did stop, we were stood on the glass of the windows but the carriage was just full of earth."
She says the first emergency services arrived on the scene within 10 minutes.
Ioannou says that those injured were treated at the scene and some taken to local hospitals.
There is still significant emergency response this evening involving British Transport Police (BTP), Sussex Police, the ambulance service and Network Rail.
She pays tribute to the BTP officers and to the emergency workers who worked in the challenging heat.
She also thanks the local community and shopkeepers for their kindness in supporting the response.
British Transport Police Chief Superintendent Dominique Ioannou is giving an update on the derailment.
She says a number of passengers were initially trapped but were all safely evacuated from the train.
She says while two people sustained serious injuries, a further 18 suffered less serious injuries.
British Transport Police's chief superintendent Dominique Ioannou and the ambulance service are giving an update now.
Watch it live here.
Aerial footage shows derailed train
We're expecting British Transport Police to give an update at 9pm.
Watch the statement live here.
National Rail says major disruption between Lewes and Haywards Heath will continue "until further notice".
Southern says it has requested rail replacement buses, although these have not yet been confirmed.
Passengers can use their tickets on a number of alternative routes, including:
Passengers are advised to check before travelling as disruption continues across the network.
Joe Coughlan
Live reporter
Image source, PA MediaA major incident has been declared following a train derailing between Haywards Heath and Lewes in East Sussex shortly before 16:00 BST today.
Emergency services have said about 150 people were on board the train, with two people sustaining serious injuries and a further nine with less serious injuries. All of the passengers have evacuated the train.
Photos from the site show emergency workers around the train on its side in a field next to the tracks, with one passenger saying it "felt like a car crash" and another saying the train derailed from carriage five.
Operator Southern Railway has told passengers "do not travel" in the affected area for the rest of the day, with the Rail Accident Investigation Branch (RAIB) saying it has deployed a team of inspectors to the site.
Rozina Sini
BBC News
Image source, Charlie HobdenPassengers stand on the side walls of the train, with the seats above their heads, after it tipped over
Charlie Hobden, 31, from Lewes, was also on the train and said it "felt like a sliding snake", adding: "We just went over and we were dragging along the floor.
"We tried to open the doors and then we saw people standing on top of the train and so we managed to get out on our own. Others waited and got on ladders to get out.
"Then the emergency serves helped us out and got we got assessed. I didn't have any injuries so I was allowed to go home."
British Transport Police has confirmed that a major incident has been declared following the incident on Thursday afternoon.
The force said a number of passengers became trapped on the train but they have now been "safely evacuated".
Assistant Chief Constable Ian Drummond-Smith said: "We've declared a major incident and a significant emergency service response is ongoing at the scene, but all passengers on the train have now been safely evacuated from the service.
"Our thoughts are of course with everyone affected, and I’d like to reassure the public that we’re supporting the Rail Accident Investigation Branch to establish exactly what's happened.
"We’ll provide further information as soon as we are able."