A suspected terror attack on a train left 10 people with knife wounds on Saturday night, sparking a massive armed police response.
Two people were arrested by officers at the scene of the horror near Huntingdon in Cambridgeshire, with the injured taken to hospital with stab wounds.
The stabbing spree was swiftly designated a Code Plato incident by senior officers, the name given to 'marauding terror attacks' - the code word was used in the wake of the Manchester synagogue stabbing.
Thirty officers rushed to the London North Eastern Railway (LNER) train after it stopped in the Cambridgeshire town. Several people have been hospitalised.
The train was the 6.25pm service from Doncaster to London King's Cross, British Transport Police confirmed.
The attack is believed to have begun shortly after the train left Peterborough station, with travellers hiding in toilets as one suspect carried a 'big knife', witnesses have said.
Videos have also emerged on social media showing police cars racing to the scene as armed officers raced to the platform.
A passenger named Gavin recalled several people moving through the train, and hearing one say: 'They've got a knife. I have been stabbed.'

'They were making their way through to get away from the suspect,' he told Sky News. 'They were extremely bloodied.
'That person, when we pulled in, they were basically on the floor; we couldn't progress further down the train because that person ended up collapsing.'
He added: 'We were ushered out of the station from the platform, and there were multiple people who had been stabbed who were making their way down.'
Passengers were then escorted off the train onto the platform at Huntingdon, he said.
'The armed police were pointing to the suspect as we came off the train.'
Train operator LNER issued a 'do not travel' warning to passengers, saying 'disruption is expected until the end of the day'.
In the hours after the attack, forensic officers could be seen apparently searching for clues on the track at the side of the train which still had its lights on.
Other paramedics and emergency service personnel were seen on the platform beside the train.
More than a dozen police, ambulance and incident support vehicles including several with blue flashing lights remained gathered in the main car park of the station.
Another four police cars blocked entrances to the car parks either side of the tracks to stop onlookers from approaching.
A large group of officers were seen outside the entrance to the main station beside what appeared to be a pile of first aid equipment.
Prime Minister Sir Keir Starmer described the 'appalling' incident near Huntingdon as 'deeply concerning'.
'My thoughts are with all those affected, and my thanks go to the emergency services for their response,' he said in a statement.
The A1307 in the direction of the town centre has also been closed as the incident remains ongoing, Cambridgeshire Constabulary said.
'Anyone in the area should follow the advice of the police.'
Elsewhere, Home Secretary Shabana Mahmood said she was 'deeply saddened' by the stabbings.
'My thoughts go out to all those affected. Two suspects have been immediately arrested and taken into custody,' she said.
'I am receiving regular updates on the investigation. I urge people to avoid comment and speculation at this early stage.'
Two air ambulances, as well as critical care teams, also swarmed to the scene.
Secretary of State Heidi Alexander echoed her colleagues' messages while adding that she was being updated on the matter and is working closely with the BTP.
Tory Party leader Kemi Badenoch said: 'Deeply disturbed by the reports emerging from Huntingdon.
'This is an absolutely horrific attack and my thoughts are with all those affected including the emergency responders at the scene.'
Chris Philip, the shadow Home Secretary, added: 'Horrific scenes in Huntingdon, in what seems to be a brutal mass attack by two perpetrators,' he said.
'My thoughts are with all those injured or affected and the emergency services responding.
'The police and government should provide an update on what happened and who has been arrested as soon as possible.'
Local Labour councillor, Alex Bulat, voices her sympathies for those affected amid ongoing reports.
'Really worrying,' she wrote to Facebook, 'My thoughts are with the victims and their families.'
Huntingdon MP Ben Obese-Jecty also said via X: 'I am aware of the incident and am trying to establish further information.
'My thoughts are with the victims and those involved.'
A spokesperson for British Transport Police said: 'We are currently responding to an incident on a train to Huntingdon where multiple people have been stabbed.
'Officers are in attendance alongside @CambsCops and two people have been arrested.
'Further updates will be shared here.'
An East England Ambulance Service spokesperson said: 'We were called at 7.38pm to reports that multiple people had been stabbed on a train.
'We mobilised a large-scale response to Huntingdon Railway Station which included numerous ambulances, tactical commanders, our Hazardous Area Response Team and critical care teams including the East Anglian Air Ambulance, Essex and Herts Air Ambulance and Magpas Air Ambulance
'We can confirm we have transported multiple patients to hospital.'
Train firm LNER said via X: 'Due to the emergency services dealing with an incident at Huntingdon all lines are blocked.
'Train services running through this station may be delayed. Disruption is expected until the end of the day.
'Please check before you travel.'
Elsewhere, several train routes have been impacted, including Hull Trains to Hull and LNER trains to Lincoln, Doncaster, Leeds, Bradford Forster Square, and Harrogate.
Thameslink trains between Horsham, Kings Cross and Peterborough have also been affected.

