One person lost their life and 89 others suffered injuries after two passenger trains collided south of Bedford on Friday evening.
The 16:40 service from Corby to London St Pancras ran into the rear of the 15:50 train from Nottingham to London St Pancras near Elstow around 5:12pm.
British Transport Police declared a major incident and called in emergency teams, including air ambulances.
First responders reached the scene quickly and treated passengers on site before moving many to hospital.
Officials report 11 people with very serious injuries and 22 with serious ones.
Services between Luton and Bedford remain closed while teams investigate why the rear train did not stop.
Rail experts note the line uses modern signalling, so authorities now examine what went wrong.
Prime Minister Keir Starmer and Transport Secretary Heidi Alexander sent messages of support to those affected and the teams working at the site.
Passengers faced major disruption on Friday evening.
East Midlands Railway confirmed no trains will run on the affected stretch for the rest of the day.
Recovery work continues as investigators gather evidence from both trains.
This incident highlights how quickly rail travel can change in a moment.
Officials promise a full report in the coming days.
