More than 80 people received treatment after the crash and 28 remain in hospital.

At least nine people remain in critical condition after two passenger trains crashed into each other and killed one driver near Bedford, about 56 miles (90km) north of London.

British Transport Police said on Saturday that more than 80 people had received hospital treatment on Friday night after the trains collided.

“As of this morning, 28 remain in hospital, and nine are in a critical condition,” Chief Constable Lucy D’Orsi said.

She added that “specialist investigators from British Transport Police are working with colleagues at the Rail Accident Investigation Branch (RAIB) to gather the facts and determine what has happened”.

Moreover, Transport Secretary Heidi Alexander said that it was “too early to speculate” on the cause of the crash, and promised that “a thorough investigation … to ensure that lessons are learnt” would be launched.

Friday’s crash involved two London-bound trains on the same track, according to East Midlands Railway (EMR), which operates both services.

On Friday, police confirmed that the driver of one of the trains had died at the scene.

In a statement from Buckingham Palace, King Charles said he was “greatly saddened” by the incident and sent “his thoughts and sympathies” to the dead driver’s family and to those injured.

The East of England Ambulance Service said on Saturday that 11 people sustained “very serious” injuries, while a further 32 suffered serious wounds and 56 others had minor injuries.

EMR’s managing director, Will Rogers, also called the crash “a profoundly sad day for the railway community”.

“We are deeply saddened that our driver has tragically died, and a number of other people have suffered injuries,” he said, speaking at the scene alongside other officials.

He added that EMR was “fully supporting” the RAIB probe.

More than 20 ambulances, specialist hazardous area rescue teams and six air ambulances were dispatched to the scene of Friday’s crash.

While the investigation continues, officials have not said whether signalling issues played a role in the incident.