Failings at a scandal-hit Staffordshire hospital trust were "completely unacceptable", Prime Minister Gordon Brown has said following the publication of a damning report.
The Mid Staffordshire NHS Foundation Trust, which runs Stafford Hospital, lost sight of its responsibility to provide safe care, the independent inquiry found.
Mr Brown told MPs the Government was working on plans to "strike off" hospital managers responsible for failures.
At Commons question time, he said more than 300 individual cases were being investigated after the scandal was exposed.
He said: "What happened in this hospital was completely unacceptable. What happened was a management failure in this hospital."
The investigation was launched into events at Stafford Hospital after another report last March from the Healthcare Commission revealed a catalogue of failings at the trust, which also runs Cannock Chase Hospital.
Appalling standards of care put many patients at risk, and between 400 and 1,200 more people died than would have been expected in a three-year period from 2005 to 2008, the commission found.
Inquiry chairman Robert Francis QC made 18 recommendations for both the trust and the Government in his final report after hearing evidence from more than 900 patients and families.
But at Prime Minister's Questions, Tory leader David Cameron said the families of victims "will never be content with an inquiry that was conducted in private".
Mr Brown said: "We understand both the sadness and the sorrow of all the relatives who lost loved ones in the Mid Staffordshire Hospital Trust.
"We know that every single one of those cases where relatives have doubts or questions are now being investigated as individual cases.
"I understand that there are more than 300 cases that are being investigated and every one of these families deserves to have the answers that are necessary.
"That is the first form of inquiry that is being done. The second form of inquiry is the Francis inquiry, which ... will continue its work on the regulation and the supervision of foundation hospitals and particularly of this hospital."
Mr Brown said he was "shocked" by reports that there were shortages of consultants and nurses on duty in accident and emergency wards.
"This is a failure in management that has got to be dealt with."
Health Secretary Andy Burnham has brought forward proposals "including a recommendation that where management fails, just as with doctors, we will be able to strike off the managers from a list of those who are acceptable for health authorities".
Mr Cameron said: "One of the tragedies of Stafford is that people were dying because of this bad practice, not just bad management but bad clinical practice and an over-adherence to processes year after year after year.
"Death rates at the hospital were far too high and out of line from 2005 yet the Healthcare Commission only started investigating in 2008."
A better way of publishing results and patient outcomes was needed, Mr Cameron said.
"We need openness, clarity and transparency to stop this happening again."
Mr Brown said action had already been taken, including new quality tests for foundation trusts and the creation of an "early warning system".
An inquiry will be launched into mortality ratios and "whether that is the best way of judging whether a hospital is being successful".
Disciplinary hearings were being carried out in relation to the Staffordshire scandal, Mr Brown added.
"We have done everything we can to ensure that after this has been exposed, we not only investigate the individual worries of families who are affected but also learn every lesson possible so that this would not happen again."
The Care Quality Commission said there was "no reason to believe" there was another English trust with problems on the "scale and magnitude" of Mid Staffordshire, Mr Brown told MPs.