Firefighters who heard the Manchester Arena bomb go off were sent away from the scene despite a paramedic arriving within 11 minutes, a report says.
“Out of the loop” crews took two hours to attend the scene of the deadly blast, which killed 22 people last May.
A report by Lord Kerslake found poor communication meant chief fire officers were “risk-averse” and kept emergency trained responders away.
The fire service’s chief apologised “unreservedly” for the failures.
Suicide bomber Salman Abedi detonated a home-made device at 22:31 BST as 14,000 people streamed out of an Ariana Grande concert on 22 May, leaving more than 700 injured.
According to the report, the first North West Ambulance Service (NWAS) paramedic arrived at 22:42 and was told the incident was a “suicide bomber” by police.
A police duty inspector declared Operation Plato, a plan for dealing with a suspected marauding armed terrorist, and wrongly assumed others were aware.
Despite protocol allowing emergency workers to continue treating the injured, a senior fire officer “stuck to rules” and kept emergency responders 500m (1,600ft) away from any zone of danger.
It was “fortuitous” the ambulance service was not informed, otherwise it might have pulled out paramedics who instead stayed and saved lives, the 226-page report said.
The report also said the fire officer was unable to get through to the force duty inspector.
As a result, Greater Manchester Fire and Rescue Service (GMFRS) was “brought to the point of paralysis”, to the “immense frustration on the firefighters’ faces”.
The fire service and the control room “felt they had let down the people of Greater Manchester” on the night of the blast, Lord Kerslake’s report said.
The report made more than 50 recommendations but states its panel of experts was not there to answer the question of: “Would the earlier arrival of GMFRS at the scene have made any difference to the medical outcomes of the injured?”
“This is a question that only the coronial inquests can decide,” the report said.
Failings in “operational culture”
Speaking after the report’s publication, Lord Kerslake said the “unspeakable attack” had been a “brutal and real-world test” of the emergency services’ response.
He said “not one single reason or one individual” was to blame for the errors, but a “most unfortunate combination” of “poor communications and poor procedures”.
Lord Kerslake said that “deep down” the errors were prompted by failings in “operational culture”.
But he conceded that it was “quite extraordinary that [the fire service] did not pick up what was happening.”
“They should have gone forward not back,” he said.
“The firefighters wanted to go forward but they were not able to. The discipline of the fire service meant that they could not self-deploy.”