Six men were fighting for their lives yesterday and another 12 were undergoing treatment for serious burns and shrapnel injuries from the crude but deadly device. Three underwent leg amputations.
Professor Gus McGrouther, a consultant plastic surgeon at University College and Middlesex Hospitals, said five young men, all of whom remained unconscious, were so badly injured that staff had been unable to identify them. There was still a very serious danger that some would lose their lives.
The worst injured would certainly be mutilated for the rest of their lives and would need months of repeated surgery to recover. "They are not going to get better in a week or a month. They are going to have scarring and great mutilation for life."
The bombing had to be stopped, he added. "It is a terribly evil thing to let off a bomb which contained fragments of particles in a confined space. That is quite simply an attempt to maim, disfigure and kill, not a political act. These people's lives have been ruined."
Hospital staff said the kind of injuries they were seeing were rare in civilian life and even worse than some of those suffered by victims of the Birmingham pub bombings and the King's Cross fire.
"Handfuls" of glass, nails and fragments of metal had been removed from wounds, and Prof McGrouther said the device must have been packed with sharp debris in a manner that was prohibited by the military worldwide. "Even in war times, these sort of injuries are outlawed," he said.
The hospitals made urgent appeals for blood donors after using thousands of units of blood while operating on the bomb victims.
Two patients remained in intensive care at UCH. Another two were in intensive care at the Middlesex Hospital and a further two at St Thomas's, which was also treating another five of the injured.
Three men with minor burns and cuts were treated at the Royal London Hospital in Whitechapel and a burns victim was at the Chelsea and Westminster. Another four men with serious burns were at St Andrew's, Broomfield, Essex, and the Queen Victoria Hospital in East Grinstead, Sussex.
When some of the men were admitted, it was impossible to establish their identities and they were simply given numbers. All were "youngish fit men" and one was thought to be Italian.
The grief-stricken friends and families of the most seriously injured men at the hospitals were being counselled by police last night, taking the pressure off hospital staff.
A man whose 28-year-old friend was last night in intensive care at UCH, after his left leg was amputated above the knee, spoke of his incomprehension at what the bombers had done. "I just feel sheer disbelief - it seems an insane action," said the man, who did not want to be named. "I don't know where all that hatred comes from."
His friend, who worked in catering, was under heavy sedation. "He can't give a reaction, but the nurse said he would be able to hear me so I am just talking to him," said the man. "We just have to wait and see what happens - there's nothing else we can do."
Two hundred extra staff, including doctors from the Royal Free Hospital in Hampstead, north London, were drafted in to UCH to help the injured, while an extra 50 were on duty at St Thomas's.
A UCH spokesman said that the staff, who expected to continue working all weekend, had been very shaken by what they had witnessed, despite training to deal with such incidents.
Jack Straw, the Home Secretary, arrived at UCH during the afternoon to meet staff, and later went on to St Thomas's accident and emergency department to visit some of the victims.
He paid tribute to the staff. "I would first like to emphasise my huge admiration for the police, the ambulances and the fire service who attended the scene and the medics, nurses and other staff of the UCH and other hospitals.
"They have all responded magnificently to what was a desperate and terrible situation."