At one point 154 casualties of a collision which killed at least 26 people were being treated at seven hospitals around London.

The most serious casualties were initially taken to St Mary's Hospital, next to Paddington station. They were suffering from burns and crush injuries to the chest and abdomen.

Five people are in intensive care at St Mary's after undergoing surgery. The hospital has another 15 patients from the crash.

On Tuesday, it treated 46 patients, at least five of whom were transferred to specialist burns and head injuries units.

The BBC's John McIntyre reports on the efforts of the hospitals the casualties were taken to

Three are critically ill in intensive care and two others are in a comfortable condition. One woman has suffered 70% burns to her body, a man has 60% burns.

Other burns victims were ferried by air ambulance to the St Andrew's plastic surgery and burns unit at Broomfield Hospital, Chelmsford.

Minor injuries include burns to the face, upper airways and upper arms, limb fractures and whiplash. Patients are also suffering from shock.

Two patients have suffered ruptured spleens.

Dr Anil Awasti: "Patients suffered severe burns"

Robin Touquet, an accident and emergency consultant at St Mary's Hospital, said: "Injuries are among the worse I have seen in my professional career.

"It was like looking after people from an air crash, but it was a train crash."

Five other London hospitals, including the Hammersmith and the Central Middlesex, also took patients.

Five victims were being kept overnight at the Central Middlesex, most suffering from smoke inhalation..

A man and a woman were receiving emergency care at the Charing Cross Hospital.

Patients were ferried to hospital as quickly as possible

Dr Peter Holden, press spokesman for the British Association for Immediate Care, said the injuries sustained in train crashes can be among the most serious of any type of accident.

He added that many people were standing up on trains, and so could be thrown the length of the carriage without any protection if there was a high impact.

Also the heavy engineering associated with trains could make it extremely difficult for the emergency services to free trapped people.

The problems were also compounded by the huge amount of glass present in most trains which could cause severe lacerations, he stated.

Dr Holden said: "If you are thrown the length of a carriage it is just the same as being knocked down by a car, except you are then also hit by everybody else and everything else in the carriage, and then probably also showered with glass."

Dr Holden said a person caught up in a serious train crash will suffer three types of damage:

• That caused by being thrown across a carriage
• That caused by others smashing into you
• That caused by the body's organs crashing against the body's other internal structures

Crush injuries

People are trapped in the wreckage

In a train crash crush injuries are often the most serious problem, and may often require urgent surgery.

Organs can be severely bruised, lacerated, or even ripped away from their vital blood supply, causing internal bleeding which can rapidly lead to death.

Haemorrhagic shock is another serious concern. Head and limb injuries are a common problem, as are the effects of smoke inhalation.

Medical officers arriving at the scene of a train crash are trained to "do the most for the most".

This means rapidly assessing the severity of people's injuries, and categorising them as either requiring delayed treatment, urgent treatment (two to four hours), immediate treatment or being dead.

The definition depends on whether a patient can breathe and whether they have proper circulation.

Doctors' top priority is to attempt to establish a working airway, and they will hook those patients who require it to an intravenous drip and to an oxygen supply.

However, the top priority at the scene of a crash is not to administer medical treatment, but to stabilise patients and to transport them to hospital as quickly as possible

Dr Holden said: "People who are yelling and screaming are not your first priority. It is the quiet ones that are - at least those who are screaming can clearly breathe and have a circulation."

Burns treatment

The top priority for people who have suffered burns is to get them to hospital as quickly as possible so that their injuries can be assessed and doctors can ascertain whether they are able to breathe unaided and whether lung damage has reduced their ability to get sufficient oxygen into the body.