Only half the ambulances available were sent to help victims of the 7/7 bombings, the inquest into the attacks has heard.
London Ambulance Service (LAS) also held back crews stationed near the scenes of the atrocities, meaning the injured had to be treated by paramedics who travelled in from outside the capital, the hearing was told.
There were 201 rostered ambulances available to LAS controllers on July 7 2005, but only 101 were deployed to the sites of the terrorist attacks on three Tube trains and a bus.
Further medical crews from outside London were sent to help the rescue effort and volunteer ambulances also assisted with treating and carrying the wounded to hospital.
The inquest has heard that some paramedics complained they were left to watch the events unfold on TV for more than an hour before being sent to help survivors.
Jason Killens, LAS’s deputy director of operations, said some crews were deliberately held back in case there were further attacks.
He said: “Given the circumstances we were facing, we made a decision not to deploy all available ambulances to the incident scenes and essentially held back in reserve other assets for any future incidents which may occur.
“I believe that was the right decision on the day and if faced with a similar set of circumstances again, it is highly probable that we would hold in reserve assets to respond if further incidents take place.”
Christopher Coltart, barrister for seven families of those killed in the suicide attacks, said LAS’s internal debrief process had uncovered problems in deploying available crews to the King’s Cross and Aldgate bombings.
Mr Killens replied: “It’s recognised that there were ambulance crews in the immediate vicinity of the scenes that were not deployed. As I say, 999 calls were still going on and it would not be appropriate to deploy every single resource in the immediate vicinity of those incidents to them. That said, I do accept that there were delays in activating available resources to the scenes.”