A Kentucky boys' school closed its campus on Tuesday over security concerns as fallout continues over a videotaped encounter involving white teenagers, Native American marchers, and a black religious sect that trended on the internet.

The school is expected to reopen on Wednesday.

Videos that initially generated outrage on social media were tightly focused on students wearing "Make America Great Again" hats, who seemed to laugh derisively as they surrounded an elderly Native American beating a drum.

Longer videos later revealed the drummer - Omaha Nation elder Nathan Phillips - had intervened between the boys and a black religious sect. That came after the teens seemed to grow rowdier and the black street preacher who had been shouting racist statements against both groups escalated his rhetoric.

Albert Running Wolf, a Native American from Fort Thomas, Kentucky, referred to Phillips during a small protest outside the school on Tuesday as "an honourable man" who was trying to be a peacemaker, but ended up being verbally attacked.

He said Phillips deserves an apology.

"It doesn't matter what colour they were, what political factions they were. It was disrespect - straightforward."

Protesters ended the rally on a street corner near the Catholic school by singing a song from the American Indian Movement while two Native Americans beat drums.

'A life lesson'

Kathleen Seither of Cold Spring, Kentucky, said she attended the rally in support of Native Americans, appalled by the students' behaviour. "They have embarrassed their school, their city, their parents, their state, their country."

Seither said their actions are an example of "white male privilege; a product of everything in today's world, including the president".

A smaller group supporting the teens converged closer to the diocese building.

Among them was Cincinnati resident Maureen Green, a former Catholic and mother of three whose sign read: "I stand with the boys. Facts not fiction."

She said she thought the boys had been mispresented and "railroaded" by some media accounts.

"I think these boys are learning a lot about how the world really works. It's a life lesson," she said.

The diocese, which previously criticised the students' behaviour, promised to begin its investigation of events last week.

"This is a very serious matter that has already permanently altered the lives of many people. It is important for us to gather the facts that will allow us to determine what corrective actions, if any, are appropriate."

Twitter outrage

An Indigenous Peoples March in Washington, DC, on Friday coincided with the March for Life, which drew thousands of anti-abortion protesters, including the boys' group from Covington Catholic High School in Park Hills, Kentucky.

In another video posted on Twitter, an Indigenous Peoples March protester shouts: "Just because you stole the land don't make it yours," to which a student wearing an Owensboro Catholic High School logo responds, "Land gets stolen, it's how it works. That's the way of the world."

President Donald Trump tweeted on Tuesday the students "have become symbols of Fake News and how evil it can be", but he added he hopes the teens will use the attention for good, and "maybe even to bring people together".

The president's press secretary, Sarah Huckabee Sanders, said the White House contacted the Kentucky students.

"We've reached out and voiced our support," Sanders said. She added no one understands better than Trump when the media jumps to conclusions and "attacks you for something you may or may not have done".

Phillips, for his part, offered to visit the boys' campus for dialogue on cultural appropriation, racism and the importance of listening to and respecting diverse cultures.

"Let's create space for the teaching of tolerance to happen," Phillips said statement said, according to The Cincinnati Enquirer.

"I have faith that human beings can use a moment like this to find a way to gain understanding from one another."