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By midmorning Tuesday, the Twitter posts in defense of the Fox News anchor Megyn Kelly were rolling in from her colleagues, one digital burst of support after another.

From Dana Perino, a co-host of the Fox News program “The Five”:

The intelligence, class & grace of @megynkelly shined last night after her week's vacation with her family. I'll be on #kellyfile Wed night. — Dana Perino (@DanaPerino) August 25, 2015

From Brian Kilmeade, “Fox & Friends” host:

i like @realDonaldTrump but his personal & professional attacks on @megynkelly r unwarranted-unacceptable- has 2 stop- @foxandfriends — Brian Kilmeade (@kilmeade) August 25, 2015

And from Bret Baier, Fox News chief political anchor who, along with Ms. Kelly and Chris Wallace, moderated the first Republican debate this month:

It's been 19 days since the debate- @realDonaldTrump has made his feelings clear. But THIS needs to stop //t.co/8BmVPZTGdp #let-it-go — Bret Baier (@BretBaier) August 25, 2015

When Donald Trump had first attacked Ms. Kelly following the first Republican debate — which drew record ratings for the network and where Ms. Kelly asked him a pointed question about his treatment of women — the response strategy seemed clear: Fox News, and Ms. Kelly, planned to take the high road.

Roger Ailes, the Fox News chairman, issued the first of several statements of support for Ms. Kelly the day after the debate, and Ms. Kelly herself briefly addressed the real estate mogul’s criticism of her — which included comments where he seemed to imply she might have been menstruating during the first debate — on her show the following week.

She said Mr. Trump felt her questions had been unfair, before agreeing to disagree and concluding, “I’ve decided not respond” and “I certainly will not apologize for doing good journalism.”

But when Mr. Trump, unprompted, again went after Ms. Kelly Monday night in a series of nasty Twitter messages, including retweeting a missive that called her a “bimbo,” the outcry from both inside and outside the network was swift.

As his employees began showing their support of Ms. Kelly, Mr. Ailes also issued a statement, saying that “Donald Trump’s surprise and unprovoked attack on Megyn Kelly during her show last night is as unacceptable as it is disturbing.”

Mr. Ailes said:

“Megyn Kelly represents the very best of American journalism and all of us at Fox News Channel reject the crude and irresponsible attempts to suggest otherwise. I could not be more proud of Megyn for her professionalism and class in the face of all of Mr. Trump’s verbal assaults. Her questioning of Mr. Trump at the debate was tough but fair, and I fully support her as she continues to ask the probing and challenging questions that all presidential candidates may find difficult to answer. Donald Trump rarely apologizes, although in this case, he should. We have never been deterred by politicians or anyone else attacking us for doing our job, much less allowed ourselves to be bullied by anyone and we’re certainly not going to start now. All of our journalists will continue to report in the fair and balanced way that has made Fox News Channel the number one news network in the industry.”

And more Fox personalities also chimed in, like Sean Hannity.

My friend @realDonaldTrump has captured the imagination of many. Focus on Hillary, Putin, border, jobs, Iran China & leave @megynkelly alone — Sean Hannity (@seanhannity) August 25, 2015

Katie Packer, a partner at Burning Glass, a Republican consulting firm that specializes in messaging to women, said that Mr. Trump’s latest round of attacks seemed to have drawn such ire for coming seemingly out of the nowhere, “just totally unprovoked.”

“She has just been so classy about it, and has just not engaged, has not responded,” Ms. Packer said. “He’s consumed by her and consumed by anyone who dares to challenge him. It just seems like so petty and juvenile to pick this up again and to call her a bimbo — just grow up.”

In a statement of his own, Mr. Trump attacked Mr. Ailes’s defense of his top talent.

“I totally disagree with the Fox statement,” Mr. Trump said. “I do not think Megyn Kelly is a quality journalist. I think her questioning of me, despite all of the polls saying I won the debate, was very unfair. Hopefully in the future I will be proven wrong and she will be able to elevate her standards to a level of professionalism that a network such as Fox deserves.”

Ms. Kelly herself is not expected to respond.