After a weekend marked by bitter recriminations over race and political bias, with the nation transfixed by viral videos depicting a confrontation between a crowd of Catholic schoolboys and a Native American elder, calls went out Monday — the federal holiday celebrating the life of the Rev. Martin Luther King Jr. — for restraint.

In the Twittersphere, a warning not to leap to conclusions gained currency across the political spectrum. As the events in question grew murkier, some who had reacted angrily sought to muffle their own social-media megaphones, chastened by yet another illustration of how the Internet widens the ideological differences among Americans, sowing confusion and discord. “This whole nation needs to take a deep breath before rushing to judgment,” advised Dana Loesch, the spokeswoman for the National Rifle Association, who is hardly known for her mild approach to rhetorical combat.

But for President Trump, the dispute was not to be missed. It offered red meat to a president who has eagerly stoked the culture wars, while seizing every opportunity to discredit the news media.

Weighing in Tuesday morning on Twitter, Trump described Nick Sandmann, an 11th-grade student at Covington Catholic High School in Park Hills, Ky., and his fellow students as “symbols of Fake News and how evil it can be.” Yet he also suggested that the Catholic teenagers could use the attention to “bring people together.”

That the students at the center of the latest controversy over race and political malice were wearing hats trumpeting his campaign slogan, “Make America Great Again,” put Trump at center stage. That their cause found support on the president’s favored television channel made his input all but inevitable.

The president first entered the fray on Monday night, lending his support to a campaign to vindicate the students, whose cause has been taken up by conservative media and a GOP-linked public relations team. Trump tweeted in defense of Sandmann, who was censured on social media when early footage of the Friday encounter in front of the Lincoln Memorial showed him grinning as an Omaha elder, Nathan Phillips, 64, beat a drum in prayer.

The all-male college preparatory school was closed Tuesday because of security concerns, according to a local Fox News affiliate, which cited a letter from the principal, Robert Rowe. “After meeting with local authorities, we have made the decision to cancel school and be closed on Tuesday, January 22, in order to ensure the safety of our students, faculty and staff,” the letter stated.

Local officials say they are investigating threats of violence against the school and individual students. Kenton County Commonwealth’s Attorney Rob Sanders said he cannot say anything more about the nature of the threats and did not answer questions about who investigators believe were behind them or who were targeted.

Members of the American Indian Movement Chapter of Indiana and Kentucky condemned threats of violence against the students.

“That’s horrible. Any threat of violence against a child is completely, completely wrong.” said Lance Soto, co-chair of the group.

Soto said the group is holding a “peace vigil” Tuesday outside the Catholic Diocese of Covington, which he said has not reached out to the organization or other indigenous people in the area.

“We would like to say, ‘We are here. There is an indigenous community here that you can reach out to,’” he said.

Thomas Pearce, also a co-chair of the group, blamed Trump for the clash at Lincoln Memorial and for the fallout that followed.

“I think it was something that happened in an environment that was filled by hatred from our president ... That’s all I can say,” Pearce said.

Trump blamed the media, which he said was responsible for “early judgements proving out to be false.”

Trump’s verdict appeared to draw on Tucker Carlson’s segment Monday night on Fox News. It signaled the White House’s endorsement of a rival narrative, which first took shape on Reason.com, the libertarian website, after fuller video of the encounter emerged.

The opposing account casts the teenager and his classmates as victims twice over, not just of verbal abuse on the Mall but also of online vilification drawing on headlines that appeared to reach conclusions about the episode based on incomplete evidence.

At first, politicians sounded the alarm. Celebrities professed outrage. School officials joined the Catholic Diocese of Covington in apologizing for the students, who were threatened as their private information poured out online.

But the tides shifted over the weekend as additional footage emerged, showing that the standoff came on the heels of an encounter with a group of Hebrew Israelites, who believe black Americans are God’s chosen people. The African American protesters, several of whom said the students had mocked them, directed racial and homophobic invective their way, videos show. So, too, did the extended footage reveal behavior by the students that some considered a confirmation of their wrongdoing.

Organizers of the March for Life, an annual antiabortion event that had drawn the teenagers to the nation’s capital, initially called the students' behavior “reprehensible,” but in a revised statement Sunday said, “It is clear from new footage and additional accounts that there is more to this story than the original video captured.” Rep. Thomas Massie (R-Ky.) praised the students, tweeting that “in the face of racist and homosexual slurs, the young boys refused to reciprocate or disrespect anyone.”

Massie weighed in again Monday to thank Trump for supporting his constituents.

“Not good, but making big comeback!” the president wrote of the treatment of Sandmann, who released a statement over the weekend maintaining that he was blameless. Trump quoted a chyron splashed across the screen during the Fox News segment, “New footage shows that media was wrong about teen’s encounter with Native American.”

Carlson criticized the media for circulating an incomplete clip, which he called “an entire morality play shrunk down to four minutes for Facebook.” He was particularly hard on conservative commentators who had joined liberals in sympathizing with the Native leader, singling out Bill Kristol, the co-founder of the now-defunct Weekly Standard magazine, for a since-deleted tweet asking his followers to mull over the “contrast between the calm dignity and quiet strength of Mr. Phillips and the behavior of #MAGA brats who have absorbed the spirit of Trumpism.”

“It wasn’t just left versus right — it was the people in power attacking those below them, as a group,” Carlson said, suggesting that Republicans had been moved to speak out to “inoculate themselves from charges of improper thought.”

Still, the partisan fault lines that seemed to shape the disagreement were reinforced on Monday, when the Louisville Courier-Journal reported that Sandmann’s family had retained the Louisville-based public relations firm RunSwitch PR. One of the firm’s partners, Scott Jennings, served in the George W. Bush administration and “is regarded as one of Mitch McConnell’s closest outside political confidants,” according to his profile for the Harvard Kennedy School’s Institute of Politics.

“You’re hardly a Trump partisan,” Carlson said of Robby Soave, an associate editor at Reason.com who joined the Fox News host on his show Monday night. Soave was among the first to question whether the Catholic teenagers were in the wrong. “It was all there,” Soave told Carlson. “You just had to watch the almost two hours of footage.”

Soave’s analysis gained broad attention over the weekend, disseminated by high-profile members of the media, such as CNN’s Jake Tapper.

“I, like many others may have reacted too quickly,” wrote Meghan McCain of ABC’s “The View,” who also shared the Reason rebuttal on Twitter. “Apologize for being part of a media pile on.”

“I Failed the Covington Catholic Test,” announced a headline in the Atlantic, where Julie Irwin Zimmerman, a writer based in Cincinnati, which lies across the Ohio River from Covington, gave voice to a media mea culpa. She said that in the future, she will reserve judgment until she has more facts, and, until then, “stick to discussing the news with people I know in real life, instead of with strangers whom I’ve never met.”

She also wrote that the story of the Catholic students and the tribal elder was a “Rorschach test — tell me how you first reacted, and I can probably tell where you live, who you voted for in 2016, and your general take on a list of other issues.”

But not everyone was convinced that a fuller picture of the events in Washington exonerated the students.

Walter M. Shaub Jr., who departed as the federal government’s top ethics watchdog in 2017 after clashing with the Trump administration, objected to Soave’s conclusion. Waleed Shahid, communications director for the left-wing Justice Democrats, argued that the earlier footage was in fact “so much worse.” And the writer and activist Amy Siskind asked why the school’s chaperones had not intervened.