Two young girls took a knee while performing the national anthem at Sunday’s Seattle Mariners game.

The school choir from Seattle’s Mount View Elementary School was invited to Safeco Field to sing the national anthem, but even as most of the kids stood to sing the nation’s theme, two girls took a knee:

Two young girls exercising their rights @SafecoField ✊ pic.twitter.com/jOOYxnHoSM — Louis Penna (@louispenna) April 1, 2018

Here at Safeco Field where an elementary school sung the anthem and two students took a knee while performing. pic.twitter.com/HwHIsowsxN — Ryan S. Clark (@ryan_s_clark) April 1, 2018

The girls’ protest follows more than two years of controversy since former San Francisco 49ers quarterback Colin Kaepernick began protesting the anthem at the start of the 2016 NFL season.

A Mount View Elementary spokeswoman told HuffPost that the protest was an “individual act” by the girls. The district also noted that it “respects [their] First Amendment rights.”

The girls have not been identified, nor have their ages been disclosed.

While protests became ubiquitous in professional football, such displays have been more rare in Major League Baseball. Though, last season, the Oakland As’ Bruce Maxwell became the first MLB player to protest the country during the national anthem.

Follow Warner Todd Huston on Twitter @warnerthuston.