Badly injured survivors of a Tube bomb had to wait an hour for help as safety rules delayed firefighters from going to their aid, an inquest has heard.
A policeman said he saw firemen waiting at the top of an escalator as the first walking wounded arrived above ground.
Crews cut open the train door to reach the injured at 1015 GMT - an hour after firefighters arrived at King's Cross station, the inquest heard.
Germaine Lindsay killed 26 people when he detonated his bomb on 7 July 2005.
Sgt Charles McGrotty and two colleagues were first sent to a report of an explosion at Liverpool Street station - but could not find anything.
They returned to King's Cross station at 0920 GMT - half an hour after the bomb went off - just as distressed passengers were reaching the surface.
The British Transport Police constable said as they descended to the Tube platforms they passed three firefighters who said they needed back-up before going down to the tracks.
Insp Kevin Johnson, who was a police constable at the time of the bombings, told the inquest it was protocol for the firefighters to wait for a second team due to communication issues.
The barrister for seven of the bereaved families, Christopher Coltart, said to him: "The firemen are standing at the top of the escalator watching the injured people come upstairs covered in soot and they have been told of an explosion on the train.
"But their protocols are preventing them from going into the tunnel until two more fire engines have arrived?"
Insp Johnson replied: "I can presume that, yes."
Sgt McGrotty was one of the first policemen at the scene. After witnessing people's injuries he ran back up to the surface to call the London Ambulance Service.
As he returned to the bombed train, he said he passed two firefighters who again said they had to wait for reinforcements before going into the tunnel.
He said: "I knew that I needed to get back down to the scene. At that time there were very few emergency services down there.
"There were two fire officers who were stood on the platform. As I went past a discussion was had about going down to the train.
"They indicated that they couldn't go down until they had their full team with their full complement of equipment."
The inquest heard that the first firefighters reached King's Cross station at 0913 GMT, but they did not go down into the tunnel until the second crew arrived at 0942 GMT.
The bomb was detonated between King's Cross and Russell Square stations.
Coroner Lady Justice Hallett said to Sgt McGrotty: "You are somebody who had been misdirected to the wrong scene, you had been up and down to the train twice, and when you get back it is possible that the fire brigade are just getting there and there are still no paramedics on the carriage?"
"That's correct," he replied.
As he arrived back at the carriage at about 0945 GMT, the first firefighters were just arriving, he said.
He estimated that by the time the firefighters had cut open the buckled door of the carriage and paramedics had got in, it was about 1015 GMT.
But Kerstin Boyd, for the London Fire and Emergency Planning Authority, said CCTV evidence suggested firefighters entered the tunnel at about 0950 GMT and removed the door within a matter of minutes.
After all the survivors were removed from the train, Sgt McGrotty volunteered to go back down and carry out further searches for bombs.
Lady Justice Hallett said he had acted way beyond the call of duty.
She said: "You acted in my view with great courage, humanity and a significant degree of professionalism, and you played a significant role in the rescue attempt, for which I commend you."
Inquests at the Royal Courts of Justice are examining the deaths of the 52 people who were killed by suicide bombers on three Tube trains and a bus.