Garfield High School's head coach told reporters that some of his players say they've encountered police brutality or racial profiling.
FULL INTERVIEW: Kaepernick addresses anthem protest'
Some opposing players, from West Seattle High, joined the protest, too.
Kaepernick began his protest in the pre-season, and other NFL players have joined him, including teammate Eric Reid.
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One San Francisco high school team also knelt during the national anthem during their game last Friday.
Denver Broncos linebacker Brandon Marshall has joined the movement. He and Kaepernick have college ties.
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