Twitter quickly lit up. “I cannot believe the ignorance on this in 2018,” wrote the “Top Chef” host, Padma Lakshmi. The comic Patton Oswalt wrote: “You and I are approximately the same age. Blackface was NOT okay when we were kids.”

A post-show meeting of Ms. Kelly’s staff turned emotional, as her colleagues expressed dismay and concern over the host’s remarks. Ms. Kelly, however, was not present to hear it: She had left for a remote shoot outside of Manhattan. And when she sent a written apology that afternoon, the note hit the internet before it landed in some of her colleagues’ inboxes.

“I’ve never been a ‘pc’ kind of person — but I understand that we do need to be more sensitive in this day and age,” she wrote in her mea culpa, which she hoped would quiet the storm. It didn’t. Three hours later, “NBC Nightly News” dedicated a segment to Ms. Kelly, citing critics who called her comments “racially tone deaf.”

‘I’m sorry’

By Wednesday morning, Ms. Kelly’s standing had gone from bad to worse.

The “Today” show devoted nearly five minutes to the “blackface” incident, complete with a clip of Ms. Kelly’s “Santa” moment from Fox News. After a montage of performers wearing blackface, Mr. Roker criticized Ms. Kelly, and his co-host Craig Melvin labeled her comments “racist and ignorant.”

The timing for Ms. Kelly could not have been worse. She was already scheduled to take off the next day — for jury duty. But Ms. Kelly now told producers to expect her at work on Thursday after all. She would postpone her jury service, so that it would not appear that she was ducking the limelight, three of the people said.

Roughly 90 minutes after Mr. Roker and Mr. Melvin spoke, Ms. Kelly opened her 9 a.m. show by saying, “I’m Megyn Kelly and I want to begin with two words — I’m sorry.” Tearing up, the host said she was “listening and learning,” before sitting with two black panelists, Roland Martin and Amy Holmes, who lectured her on the brutally racist history of blackface.

Briefly, it looked like Ms. Kelly may have turned things around. The studio audience gave her a standing ovation. A question-and-answer session after the taping went well. None of the 150 attendees, many of whom were regulars at “Megyn Kelly Today” tapings, criticized the host for her remarks, and several offered support, two of the people said.