Students wearing “Make America Great Again” caps were filmed mocking a Native American man in Washington DC.
The video shows one boy staring into the man’s face from just a few feet away as he beat his drum and sang, while other pupils laughed and jeered.
Nathan Phillips, 64, a Vietnam War veteran, was in Washington for The Indigenous Peoples March and the pupils were there for an anti-abortion event.
Mr Phillips said he heard some of the pupils chanting “build that wall” – in reference to the barrier President Trump wants to build on the Mexico border.
The behaviour in the video has been widely condemned after it went viral on the internet.
The boy, who has been identified as a student from Covington Catholic High School in Park Hills, Kentucky, was recorded being egged on by other children.
The pupils’ school and the Diocese of Covington made a joint apology to Mr Phillips and said they would take “appropriate action, up to and including expulsion” over Friday’s incident at the Lincoln Memorial.
“We extend our deepest apologies to Mr Phillips,” they said.
“This behaviour is opposed to the Church’s teachings on the dignity and respect of the human person.”
In a video posted to Instagram, Mr Phillips wiped tears away as he said: “When I was there singing, I heard them saying ‘Build that wall, build that wall’.
“This is indigenous lands. We’re not supposed to have walls here. We never did.”
Marcus Frejo, a member of the Pawnee and Seminole tribes who is known as Chief Quese Imc, said at the end of the march students had started chanting “Make America Great Again” – the president’s rallying call.
He said they also did the haka, a traditional Maori dance, which Mr Frejo felt they were mocking, before they broke up and walked away.
Mr Phillips told The Washington Post that he continued drumming as the students mocked him, thinking about his wife who died of bone marrow cancer, and the threats faced by indigenous communities around the world.
Republican Ruth Buffalo, a North Dakota representative and member of the Mandan, Hidatsa and Arikara Nation, said she was saddened to see students showing disrespect to an elder, who is also a military veteran.
“The behaviour shown in that video is just a snapshot of what indigenous people have faced and are continuing to face,” she said.
Ms Buffalo said she hoped it would lead to some kind of meeting with the students to provide education on issues facing Native Americans.
Republican Deb Haaland, who is a member of the Pueblo of Lagana and also a Catholic, placed some blame on Mr Trump who has used the name Pocahontas as a jibe against Senator Elizabeth Warren.
“It is sad that we have a president who uses Native American women’s names as racial slurs and that’s an example that these kids are clearly following considering the fact that they had their ‘Make America Great Again’ hats on,” said Deb Haaland.
(c) Sky News 2019: Native American man mocked by schoolchildren in Trump ‘MAGA’ hats