Ambulances were held back from attending some of the dead and injured in the Cumbrian shooting rampage because of health and safety laws, an inquest has been told.
And there were also problems with police and ambulance chiefs unable to communicate properly and the mobile phone network "crashing".
Thirteen ambulances, three helicopters and four rapid response cars were scrambled but some were held back for fear gunman Derrick Bird was on still on the loose, the inquest heard.
It meant some crews from the North West Ambulance Service (NWAS) did not arrive at the scene of a shooting for nearly two hours after they were first called and by then injured victims had been rushed to hospital by police.
Peter Mulcahy, the head of NWAS for the Cumbria region, said the health and safety of paramedics was "paramount".
He told the inquest into the deaths of the victims, at the Energus centre in Workington, that it would be "wholly inappropriate and unreasonable" to send unarmed and unprotected staff into an area where a gunman was on the rampage.
Police and the ambulance service also used different wavelengths on their radios so had difficulty communicating - a system that is now being replaced so all 999 services will eventually use the same wavelength, the inquest heard.
Taxi driver Bird, 52, left 12 people dead before turning a gun on himself to end the rampage on June 2, last year.
Evidence heard during the inquest, now on its 11th day, suggests none of the fatalities would have survived in any event, such were their injuries cause by a shotgun and a rifle at close range.
Mr Mulcahy said 343 firefighters had been killed in the 9/11 attack in New York after they were sent into unsafe areas. And he cited firefighters being held back after the London bombings for the same reason.