The two students stormed through the front doors at Riverton High School on Wednesday with wide grins on their faces. Both wore white robes, and the boy in front had a tall, pointy hood. He wore a large cross around his neck and waved an American flag.

When Micah Lott saw a viral image of the students later that morning, he had no doubt that they had dressed as Ku Klux Klan members — a choice all the more shocking in Riverton, a small Wyoming town surrounded by the Wind River Indian Reservation.

“I was surprised to see something this blatant,” Lott, 26, a member of the Northern Arapaho Tribe and a Native American rights activist, told The Washington Post. “Racism is a taught behavior. We have to acknowledge what we’re teaching our children and how it’s continuing this cycle in our country.”

The two students, who have not been named, were disciplined Wednesday, the school said on Facebook. State and local officials decried the photo and called for a new conversation about racist imagery.

“I am saddened and disappointed by the actions of the two students involved in the incident,” Jillian Balow, Wyoming’s state superintendent, said on Twitter. “This hurts our community, state, and nation.”

The two students wore the robes during “Spirit Day” at Riverton High, the Casper Star-Tribune reported, where a “white out” theme was encouraged. Some commenters on the school’s Facebook post about the viral image suggested the two students had intended to dress as monks.

But Balow said that’s not what school officials came to believe after investigating.

“The facts indicate that they deliberately and intentionally entered the school in attire known to be associated with the Ku Klux Klan,” the superintendent wrote on Twitter. “Hateful speech, attire, or behavior is unequivocally unacceptable.”

Riverton, a town of roughly 11,000, sits on land that was carved out of the Wind River Indian Reservation in the early 20th century, a fact that has long led to tensions between the mostly white residents and the roughly 14,000 Native Americans who live on the tribal land.

Lott said he saw that tension firsthand when he went to Riverton for school as a child.

“We were always told to ‘go back to the res,’” he said. “But then you grow up and realize, ‘What does that really mean?’ Because we’re on the reservation, we’re surrounded by it.”

Those tensions have only escalated in recent years, Lott said, amid several deadly shootings of Native American men by Riverton police officers, including a 58-year-old Northern Arapaho man shot and killed by police outside a Walmart in September.

So when some community members on Wednesday quickly insisted that the white hoods in the viral photo from Riverton High School were simply a joke, Lott found that hard to accept. Riverton High is mostly white, he said, though he estimated around a fifth of the students are Native American.

“Some people are like, ‘This is just a prank,’ but given all the context of the situation here, that’s not right,” Lott said. “It’s not okay to portray, even as a joke, that history behind the KKK. That’s not a joke, what they’ve done to people.”

As outrage built steadily on Wednesday, Riverton High administrators responded by insisting they had “handled” the situation, though they did not specify what kind of discipline the students faced.

“We do not condone or support the student’s actions. We have taken disciplinary measures and handled it,” the school wrote on Facebook. “One student’s decision does not represent our school or district.”

Terry Snyder, the superintendent of Fremont County School District No. 25, the district that represents Riverton, suggested the students didn’t appreciate how the white robes and pointed hood would be perceived.

“It seems to be a very poor decision,” Snyder told CNN. “They did not have an understanding of the impact that would create, but they do now.”

The school’s principal and faculty planned to meet Thursday to discuss how to address the incident, Snyder said. Lott said he hopes it leads to a more honest reckoning in Riverton with the town’s historic and ongoing problems with racism.

“People are just barely having these conversations right now. The wound is still very fresh,” he said. “We’re definitely moving slower here than in other parts of the country. We need to talk so we can understand each other better, and see that as indigenous people, we’re humans too.”