Passengers travelling from Doncaster to London have been attacked in a mass stabbing on Saturday night.
Ten people were injured and taken to hospital. Nine of them are believed to have life-threatening injuries.
Witnesses reported that police used a Taser on one man who was holding a knife. Two people were arrested.
Counter-terror police have joined the investigation. Prime Minister Sir Keir Starmer said the attack was "appalling" and "deeply concerning".
Here is what we know so far about what happened.
