Bereaved relatives said they were shocked by the suggestion that as many as 41 of their loved ones did not all die quickly and could have survived the crush at the football stadium, made for the first time 23 years after their deaths.
In one of the most controversial episodes of the initial investigations, a coroner ruled that the Liverpool fans must have been fatally wounded within minutes of kick-off and refused to hear evidence about the chaotic medical response after 3.15pm.
But the independent panel that had unprecedented access to 450,000 official documents about the tragedy found evidence that as many as 41 of the 96 victims did not have signs of the crush injuries originally claimed by pathologists.
Margaret Aspinall, chairman of the Hillsborough Families Support Group, who lost her son, said: "What was new and a shock to us was how many of them could have been saved.
"I'll go home and think about that and was James one of them."
Trevor Hicks said: "There's pretty strong evidence that had the response been better then certainly some people would have survived. We are staggered at the incompetence."
The families may learn for the first time when exactly their relatives died and if they could have been saved, by studying the reports published online by the panel.
It is also almost certain that the High Court will set aside the original inquest verdicts of accidental death, allowing fresh hearings to be carried out at which doctors could be questioned about the possibility of survival.
The new report shows that the coroner, Dr Stefan Popper, claimed there was only "minimal" concern among families that he only carried out "mini-inquests" on the victims.
He dismissed their questions about the 3.15 cut off - the point at which an ambulance arrived on the pitch - on the grounds that they did not understand inquests.
But the new review of post-mortem reports shows that not all of the victims died quickly and some were unconscious for a "significant" period of time, during which they could have been resuscitated.
It details the repeated attempts, rebuffed by the Attorney General's office, by the mother of Kevin Williams to have his death re-examined after a special constable said he had been alive after 3.15pm and had opened his eyes and said "mum".
Dr Bill Kirkup, a medical member of the review group, told a press conference: "Twenty eight people had definite evidence that they didn't have obstruction of the bloodflow, 16 people had definite evidence of heart and lungs continuing to function for a prolonged period after the crush.
"In total 41 therefore had evidence that they had potential to survive after the period of 3.15.
"What I can't say is how many of them could, in actuality, have been saved.
"But I can say is that, potentially, it was in that order of magnitude."
The coroner also ordered the "exceptional" recording of blood alcohol levels from all of the deceased, in an "inappropriate" attempt to show that those who arrived at the ground later had been drinking.