The families of two fire officers killed in a blast at a fireworks factory in East Sussex are entitled to compensation, the High Court has ruled.
Firefighter Geoff Wicker, 49, and fire service cameraman Brian Wembridge, 63, died in the fire at Marlie Farm, in Shortgate, in 2006.
The families claimed crews were "ill-prepared and poorly resourced" by East Sussex Fire and Rescue Service (ESFRS).
ESFRS said it would give careful consideration to the judgment.
Mr Justice Irwin has ruled in favour of families after months of considering the evidence given at a two-week trial in London in February.
The amount of the damages to be paid by ESFRS has yet to be assessed.
Retained firefighter Mr Wicker and fire service photographer and camerman Mr Wembridge were among the first at the scene of the fire at the Festival Fireworks site on 3 December 2006.
Twenty others, mainly police and fire officers, were also injured in the massive explosion at the site, which sent fireworks and debris flying across the area.
Festival Fireworks' owners - father and son Martin and Nathan Winter - were convicted of the men's manslaughter and jailed for seven and five years.
Counsel for the Wicker and Wembridge families argued there were a number of reasons why the tragedy happened.
These included lack of training for the firefighters, a lack of information about Marlie Farm and a failure of the authorities to inspect the site regularly.
The court also heard that on the day of the fire there was not enough equipment, and radios were not working properly.
Also, the whistle blown to tell firefighters to evacuate the scene could only be heard by 16% of crews at the scene.
It was also claimed there was a failure of leadership in that those in charge on the day told firefighters to withdraw when they should have been telling them to evacuate the site.
ESFRS denied negligence.
The Fire Brigades Union (FBU) said the ruling reflected "the systemic and cultural failure of those responsible for ESFRS".
"Although the ruling cannot undo Geoff or Brian's tragic deaths, firefighters can be relieved that their employers cannot merely renounce their duty of care," said general secretary Matt Wrack.
"The events at Marlie Farm were a tragedy, with two lives needlessly lost even though firefighters did a fantastic job.
"The FBU have only received the judgment today and will need to reflect on it carefully, including checking that current arrangements in East Sussex reflect the ruling.
"We appeal to East Sussex Fire and Rescue Service to avoid prolonging the agony of bereaved families as well as injured firefighters and police officers by accepting this judgment and paying the appropriate compensation as soon as possible."
Chief fire officer and chief executive Des Prichard said the High Court case brought back to the surface the sheer magnitude of the event for all those involved.
"The judge listened carefully for two weeks to the evidence but did say that this was a very complex matter and he would take some considerable time to make his judgment," he said.
"It is only right that we give due consideration to the careful thoughts of the judge and now look at that document in detail before we make a further response."