A Catholic school in northern Kentucky is investigating after video of an encounter between a group of white students wearing "Make America Great Again" hats and a Native American Vietnam veteran drew backlash online. The video was recorded Friday at the National Mall in Washington, D.C.

Nathan Phillips, a veteran who attended the Indigenous Peoples March, is shown singing and playing a drum inches away from one student. Phillips said in a video posted to Instagram that some students were chanting "build that wall."

"This is indigenous land, you're not supposed to have walls here. We never did for a millennia. We never had a prison; we always took care of our elders, took care of our children, always provided for them, taught them right from wrong. I wish I could see that energy ... put that energy to making this country really, really great," Phillips said, wiping away tears.

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The teens were identified on social media as students at Covington Catholic High School in Park Hills, Kentucky. They were in Washington, D.C., to attend the March for Life rally, an annual gathering of anti-abortion activists, which included an appearance Friday from Vice President Mike Pence.

The Diocese of Covington and Covington Catholic High School said "the matter is being investigated and we will take appropriate action, up to and including expulsion."

"We condemn the actions of the Covington Catholic High School students towards Nathan Phillips specifically, and Native Americans in general, Jan. 18, after the March for Life, in Washington, D.C. We extend our deepest apologies to Mr. Phillips. This behavior is opposed to the Church's teachings on the dignity and respect of the human person," the statement said.

They also apologized to March for Life attendees, saying the teenagers' actions had "tainted" the event, and they expressed "our most sincere apologies to all those who attended the March and all those who support the pro-life movement."

Democratic Rep. Deb Haaland, one of the first Native American women to serve in Congress, tweeted a statement condemning the actions of the students.

"This Veteran put his life on the line for our country. The students' display of blatant hate, disrespect, and intolerance is a signal of how common decency has decayed under this administration. Heartbreaking," she wrote.