A firefighter called to the 7/7 terror attacks told an inquest how "protocol" forced his team to stand by and watch as horrifically injured passengers emerged from one of the bombed trains.
Andrew Shaw was among the first to arrive at King's Cross Tube station after Jermaine Lindsay blew himself up on a Piccadilly line train.
But though desperate to head into the smoke-filled tunnel where passengers lay dying, his senior officer insisted he wait for a back-up crew.
This did not come until 9.42 - nearly an hour after the initial explosion and after it was mistakenly directed to the wrong location.
The inquest heard how the first firefighters arrived at the Underground station to see passengers with bloodied faces and covered in soot coming up from the tunnel.
Mr Shaw said he felt the "urge" to head straight to the stricken carriage but was stopped by his senior officer, Aaron Roche.
Despite knowing that a "distressed" member of British Transport Police had already been onto the train, Mr Roche still dismissed his repeated pleas to act.
"You kind of feel a bit useless when you are standing around not doing much," he said.
"You want to assist the situation and you want to just continue with the job."
Earlier, the inquests for the 52 victims of the 2005 London terrorist attacks heard how the rescue effort was hampered by confused instructions which meant a team of firefighters was dispatched to Euston Square rather than to King's Cross.
Christopher Coltart, representing seven of the victims' families, said: "In the context of what was happening that morning, that was a disaster, wasn't it, frankly?"
"It was unfortunate, yes," Mr Shaw replied.
The inquest, at London's Royal Courts of Justice, also heard how poor radios meant firefighters had to return to ground level to call for more medical supplies, something they found "deeply unsatisfactory".
Suicide bomber Lindsay, 19, killed himself and 26 others when he detonated his device on a Piccadilly line train between King's Cross and Russell Square stations in London at about 8.50am on July 7, 2005.
The inquest heard how "confusion reigned" at King's Cross in the moments after the blast.
Those first on scene were initially informed there could have been a power surge or a train crash.
When asked whether he attempted to find out what had happened from passengers as they emerged from the tunnel, Mr Shaw said: "No, we didn't and perhaps we should (have done)."
Temporary sub-officer Adam Colebrook-Taylor, who received erroneous instructions to attend Euston Square, said he ended up at King's Cross only by "lucky chance".
He told the inquest he happened to call a colleague who was at the beleaguered station and assumed this was where he was needed.
This came after the driver of his appliance accidentally sent a signal to controllers indicating that the incident at King's Cross was "closed".
Mr Colebrook-Taylor, who had been in charge at Soho fire station that day, defended colleagues who waited for back-up before going down to the bombed train.
Reflecting on how he would have handled the situation, he said: "I would still have waited for another crew to turn up."
But he hit out at superiors, telling the inquest he was "still waiting" for a formal debrief after the 2005 attacks.
"On other incidents we had been to, we always had a debrief but on this one we hadn't," he said.
The inquest was later told how London Fire Brigade's (LFB) mobilisation policies "failed" on the morning of July 7.
Although an initial call was received at 9.02am, a combination of staff adhering to "protocol" and the misdirection of crews meant firefighters did not go into the tunnel until after 9.42am.
Meanwhile, the response was described as a "split attendance" after three engines were initially dispatched to Euston Square while only one was sent to King's Cross.
Mr Coltart, who pressed witnesses over the chronology of events, told the coroner: "It's very important, in our submission, that the court understands the full extent to which we say the London Fire Brigade mobilisation policy failed on this particular morning."
Explaining LFB procedures to the inquest, Mr Colebrook-Taylor said: "Protocol is that we don't commit crews when you're really with bare minimum.
"The reason behind that is, if you send your only two crew down to an incident, whether it be sub-surface, whether it be a high rise, you've got no means of, if they got into trouble, of rescuing them.
"So it's always laid down that, you know, you have to wait for a second crew."
Coroner Lady Justice Hallet commended the work of individuals once on board the devastated train.
As Mr Shaw concluded his evidence, she told him: "Whatever I find about the protocol that prevented you going down to the train for so long, when you did get down there, when you were allowed to get down there, you obviously carried out your duties as one would expect and in most appalling conditions.
"I suspect you have tried to suppress your memory of that day and I'm sorry I have had to ask you to relive it."Reuse content