AUSTIN, Texas – CBS fired a “60 Minutes” producer and three news executives Monday after an independent review found the network violated a raft of journalistic ground rules in airing a questionable story about President Bush’s military record.

“These problems were caused primarily by a myopic zeal to be the first news organization to broadcast what was believed to be a new story about President Bush’s Texas Air National Guard service, and the rigid and blind defense of the segment after it aired despite numerous indications of its shortcomings,” the panel said.

The 234-page report reached no conclusion about the authenticity of the memos that were the basis of the Sept. 8 broadcast that implied Bush received special treatment in the Guard. But it identified “a number of issues” about their legitimacy that CBS should have – and didn’t – look into before allowing the story on the air two months before the presidential election.

The report also faulted CBS for continuing to defend the report long after there were legitimate questions about the memos and for overstating the quality of sources and measures taken to verify their authenticity.

CBS Chief Executive Leslie Moonves announced the dismissals, along with a series of other measures the panel recommended to help the network boost its journalistic safeguards. He apologized for “the disservice this flawed ‘60 Minutes Wednesday’ report did to the American public.”

The fired producer, Mary Mapes of Dallas, said Monday that she was “terribly disappointed” by the report. She defended the original Bush story, saying it was corroborated by others and consistent with previously known records.

The broadcast, narrated by anchor Dan Rather, cited documents purported to be from one of Bush’s commanders in the Texas Air National Guard. The documents said that the commander, the late Lt. Col. Jerry Killian, ordered Bush to take a medical exam and that the future president did not. Killian also reportedly felt pressured to sugarcoat an evaluation of then-1st Lt. Bush.

Questions were quickly raised about the memo. Some document experts said a font used in the document appeared to have been created on a computer and not on any typewriter that was available at the time.

The panel found “no basis” to accuse Rather or his producer of political bias in preparing the piece, which was based on documents later alleged to be forgeries.

But it said the network left itself open to such charges by rushing the story to air, abandoning numerous journalistic standards, relying on anti-Bush sources and contacting the campaign of Bush’s Democratic opponent, Sen. John Kerry of Massachusetts.

Rather, who announced in November he was stepping down as the anchor of “CBS Evening News,” was not disciplined, but Moonves criticized him for “errors of credulity and over-enthusiasm.”

The panel portrayed Rather as an overworked anchor who did little to help prepare the original report and he did not even appear to have seen it before it aired.

Because Rather is giving up the anchor chair – a decision he said was unrelated to the Guard story – further action “would not be appropriate,” Moonves said.

CBS News led its Monday evening broadcast with a 5½ minute report about the investigation and firings.

The panel acknowledged Mapes’ reputation as one of best producers in television. She produced the “60 Minutes” report last spring that showed pictures of Americans mistreating Iraqis in Baghdad’s Abu Ghraib prison.

As for her Bush story, the panel accused her of misleading supervisors about the reliability and impartiality of her chief source, retired Army National Guard Col. Bill Burkett. It also said she overstated experts’ opinions that the memos were authentic.

In a statement, Mapes defended her reporting as including “nothing false or misleading.”

She accused her bosses of putting politics and ratings ahead of journalism, and blamed them for rushing the piece, saying, “If there was a journalistic crime committed here, it was not by me.”

“Indeed, in the end, all that the panel did conclude was that there were many red flags that counseled against going to air quickly,” said Mapes, whose husband is a reporter for The Dallas Morning News.

“I never had control of the timing of any airing of a “60 Minutes’ segment; that has always been a decision made by my superiors,” including CBS News President Andrew Heyward, who kept his job.

The panel said Heyward had explicitly urged caution before the report aired.

Al Tompkins, author of a textbook on broadcast news ethics, said the report and the actions taken by CBS are sensible and effective measures to burnish the network’s credibility.

“The report itself is clear, straightforward and sharply worded,” said Tompkins, a faculty member at the Poynter Institute, a Florida journalism research center. “The people losing their jobs is an appropriate action, because of the tremendous trust that’s required to do their job.”

In addition to firing Mapes, CBS asked for the resignation of three other news bosses: Josh Howard, executive producer of “60 Minutes Wednesday”; his top deputy, Mary Murphy; and senior vice president Betsy West.