A senior paramedic sent to the 7/7 bus blast said today it was 30 minutes after arriving before he knew anyone had died.
Terence Williamson, an operations manager for London Ambulance Service, arrived at Tavistock Square after teenage terrorist Hasib Hussain blew up the No 30 bus.
The attack killed 13 innocent passengers, sending victims flying into the road from the double-decker.
Hussain, 18, detonated his homemade explosives with the bus next to the headquarters of the British Medical Association.
Doctors inside the building rushed out to help.
The inquest into the 52 victims of four attacks on London on July 7 2005 heard this week that the first paramedic arrived within minutes of being dispatched to another bombing.
By 10.05am this crew had twice phoned ambulance control to request back-up and relay news of casualties and the dead.
But crews were only dispatched at 10.42.
Today, Mr Williamson said he was sent to the scene only after reports of a second explosion at Tavistock Square.
This was in fact the controlled explosion of a suspicious package conducted at 10.40am.
He was not given the information which was phoned in earlier that day by paramedics Jessica Ashford and colleague Nadene Conway, he said.
He also said despite attending a Gold Command meeting - of high-ranking emergency services leaders - he did not know there had been a bomb on the Tube between King's Cross and Russell Square.
He said: "All I was aware of, there were multiple explosions but not any locations."
Mr Williamson said his radio did not work and communications with central ambulance control were very poor.
When he arrived it was "initially a very quiet scene with very few people around", he said.
And he added he did not know that casualties had been ferried inside the BMA's courtyard.
Under questioning from Caoilfhionn Gallagher, for some of the victims' families, Mr Williamson said he stopped at a cordon on one side of the bus when told to by a policeman.
He said he could not see any casualties behind the bus.
Asked by Miss Gallagher whether he pressed to be let through, he said: "I personally didn't try to enter the cordon area."
Paul Gibson, who was LAS's "Silver Commander" at the site, was already at Tavistock Square when Mr Williamson arrived on the far side of the square.
Mr Gibson, whose job was to manage LAS's efforts and liaise with other leaders, said he could not remember when it was he found out Mr Williamson was there.
"It would have been very helpful to have Mr Williamson's resources," he said.
"We could have established officers and managers in the command roles that I had asked crew and staff to do and allow crew staff to focus on the transport and further treatment of patients and assisted the doctors who were already doing an admirable job."
Andrew O'Connor, junior counsel to the inquest, said the explanation that ambulances were delayed getting to Tavistock Square because of traffic was "not an accurate explanation".
Mr Gibson said: "There were so many incidents going on, some vehicles were deployed to different incidents."
Mr O'Connor said: "It appears to have taken 52 minutes to deploy to the Tavistock Square bomb," and pressed for another explanation.
Mr Gibson began explaining that some vehicles were usually dispatched electronically and others manually.
"It's less complicated than that," said the barrister describing the delay as a "very serious failing that day".
Mr Gibson replied: "I can't explain exactly what happened in the control room.
"I wasn't in the control room."
Dr Peter Holden, a GP from Matlock, Derbyshire, was working inside BMA House when the fundamentalist launched his attack.
The doctor, who was present as a member of the General Practitioners' Negotiating Team, refused to be evacuated despite the BMA head of security's instructions to do so.
He threw himself into action along with a group of other doctors and established himself as "Silver Doctor", in charge of managing their efforts.
Today, he recalled the blast.
"Essentially, we heard a loud bang.
"I do remember everything going salmon pink at just about the same time and, in the main office, some of the staff beginning to make a lot of commotion, and came out of the office and could see the white smoke and the tree canopy gone."
The GP said he took a "large breath in" and the doctors looked out of a window at the horrific sight but he was worried about the impact on his colleagues.
"I looked for about half a second and I said 'It's a bomb. There's been an explosion. There are casualties. Don't look for long. Let's go.'
"I deliberately said 'Don't look for long' because of after- images."
He recalled the futility of trying to save some of the victims.
Referring to 50-year-old cleaner Gladys Wundowa, from Ilford, Essex, he said he wanted "to put off the evil moment when nature took its own course".
He added: "It was in my mind that this patient was so severely injured under the circumstances with the assets we had available that survival was highly unlikely and, even if she had been the only victim and we'd had all the resources of the metropolis at hand, survival was still unlikely."
Asked if any of the patients' conditions deteriorated because of a lack of equipment, he said: "This was not an ideal world.
"It was force majeure.
"Maybe I'm hard - you have to be to do this kind of work.
"I'm afraid, when you get an incident of this variety, there will be casualties.
"You have to take the view, if you're going to get the best result that you can, of 'Do the most for the most'.
"And that really does mean prioritisation of what you do."