In a statement released Sunday to the media, Covington Catholic High School junior Nick Sandmann, who was shown over the weekend standing face-to-face with an indigenous man Friday in Washington, D.C., said the standoff took place after four African-American protesters said "hateful things" to Sandmann and a group of his classmates.

"They called us 'racists,' 'bigots,' 'white crackers,' 'faggots' and 'incest kids.' They also taunted an African-American student from my school by telling him that we would 'harvest his organs.' I have no idea what that insult means, but it was startling to hear," Sandmann wrote.

The remark about harvesting organs may reference Jordan Peele's horror-satire "Get Out," a 2017 movie in which the black boyfriend of a white girl discovers her family is harvesting the organs of blacks.

The four African-American protesters near the Lincoln Memorial have been identified as members of the Black Hebrew Israelites.

In its magazine, "Intelligence Report," the Southern Poverty Law Center calls the Black Hebrew Israelites a hate group that is "becoming more militant."

The Southern Poverty Law Center reports, "Around the country, thousands of men and women have joined black supremacist groups on the extremist fringe of the Hebrew Israelite movement, a black nationalist theology that dates to the 19th century."

The center also reports that black supremacist groups have had success recruiting in the wake of President Donald Trump's election in 2016.

MORE: Year in Hate and Extremism report shows increases

MORE: Christian Identity group preaches white supremacy close to home

A white supremacist leader, Tom Metzger, once said of extremist Hebrew Israelites, "They're the black counterparts of us," according to the Southern Poverty Law Center. The extremist white theology is known as Christian Identity, which has had some affiliated congregations in Greater Cincinnati and Northern Kentucky.

Hebrew Israelites believe African-Americans are God's chosen people. The movement goes by several affiliated names. A Baltimore-based organization is affiliated with a central group in New York City that goes by the name of the Israelite Church of God in Jesus Christ. The sect is obsessed with hatred for whites and Jews. Baltimore is one of 29 local branches, according to the Southern Poverty Center.

"Confrontations between Hebrew Israelite street preachers and their perceived enemies are growing uglier and gaining increasing attention through video clips circulated to legions of views on websites like Youtube," the SPLC magazine "Intelligence Report" has written.

Street preachers often wear heavy robes and matching head coverings of white, red and black cloth. The Star of David emblem is sewn into their clothing and worn as medallions on necklaces.

At the national level, growth is taking place in the numbers of both neo-Nazi and black nationalist groups, according to the Southern Poverty Law Center 's Year in Hate and Extremism report released in February 2018.

The total number of hate groups increased 4 percent in one year, from 917 in 2016 to 954 in 2017. Researchers at the Montgomery, Alabama,-based civil rights law firm and civil rights organization say the growth in black supremacist groups represents a backlash to the white supremacist sentiment that Trump has stirred up.