A paramedic has admitted "precious time" may have been "wasted" as medics waited above ground for an update on casualties in the 7 July Tube bombings.
David Parnell and Steve Jones, the first to the wrecked carriage at Aldgate, took no medical equipment so they could concentrate on assessment.
Their radios did not work underground so they both returned to the surface to request life-saving supplies, the inquest into the 7 July deaths heard.
Four suicide bombers killed 52 people.
Seven died in the Tube bomb near Aldgate.
In the bombed carriage, the paramedics found six dead bodies and seven or eight seriously wounded survivors they classed as "priority one", meaning they needed immediate medical help.
Mr Parnell returned to the surface to tell waiting medics what was needed to treat the injured on the train.
He was still talking to his colleagues when Mr Jones came up from the tunnel to ask what had happened to the medical team and extra equipment they had asked for, the inquest heard.
'Pen and pad'
Mr Parnell, who in 2005 was part of a doctor and paramedic emergency team based at the Royal London Hospital in Whitechapel, east London, was designated "bronze medic" on arriving at Aldgate.
That meant he had responsibility for working with the other emergency services to save as many lives as possible.
He told the coroner at the Royal Courts of Justice that he did not take medical supplies down to the train at first because his task was to assess the situation.
"As a bronze medic, if you take medical kit with you, you start treating people," he said.
"My experience is from listening to other medical personnel who have done major incidents and have actually done a role of bronze medic, the best thing to do is take a pen and a pad."
Coroner Lady Justice Hallett questioned him about the apparent delay in treating the wounded on board the train.
She asked: "Did you know, Mr Parnell, why the medical teams weren't immediately behind you?"
He said: "At this stage we didn't know what we were dealing with.
"It is standard procedures that a bronze medic would give a full report and state what's required and what kind of equipment is required before a medical team is committed."
The coroner asked: "Here you have to run back. If you're waiting for that, isn't there the possibility that precious time could be wasted?"
He replied: "That is a possibility."
Mr Parnell said he believed that only one paramedic - Craig Cassidy - was left in the bombed carriage when he and Mr Jones came to the surface to request more assistance.
On arriving at Aldgate, Mr Parnell told other paramedics to stay at the surface, the inquest heard.
This was to ensure that the ambulance "silver commander" in charge of the incident knew where all medics were in case another bomb went off on the train.
He said: "It is standard practice that silver knows exactly how many have gone down to the incident site, and should there be a secondary device he or she would know how many resources are at that site."
Mr Parnell said he went between the surface and the bombed carriage three or four times, a journey that took three to four minutes each way.
Mr Jones, who in 2005 was a motorcycle paramedic based at Waterloo ambulance station, told the inquest he descended to the train carrying only triage cards used for marking how urgently people needed medical help.
"I understand it may seem strange for us not to take medical equipment when that's what we're trained to do," he said.
"The short time it takes for us to triage will actually benefit in the long term by finding out what injuries there are and what equipment is needed on the train."
But Lady Justice Hallett suggested that would depend on how soon afterwards people able to treat the injured followed him to the scene.
"I mean, presumably, if you're triaging in an emergency situation, you assume there's going to be somebody right behind you," she said.
Mr Jones replied: "Yes, my lady."
The inquest also heard that there was confusion about who was in charge of the emergency medical response at Aldgate.
Three ambulance officials independently called their control room to declare the bombing a "major incident".
The coroner remarked: "If you weren't careful, you would find everybody arriving would be trying to ascertain the situation and there wouldn't be anybody attending to casualties."
The inquest continues.