Colin Kaepernick joined a high school football team in its protest Friday night in Oakland, California, where numerous players were photographed lying on their backs with their hands raised while the San Francisco 49ers quarterback kneeled during the pregame playing of the national anthem.

Kaepernick visited with players from Castlemont High School and spoke with the team in the locker room before the game, telling them that "you are important, you make a difference, this matters. Everything you do matters."

Castlemont's football team gained attention in the Bay Area last weekend when players kneeled with their fists raised in the air during the national anthem.

Videos began circulating early Saturday morning on social media of Kaepernick addressing the team and thanking them for their initial protest.

"I had to come support you all, because the same way you all took a stand and stood with me, I had to come out here and stand with you all," Kaepernick told the players. "So I appreciate what you all did. I love you all. You all are my brothers, I'm here with you."

The photo of the players and coaches lying on their backs, tweeted by former NFL linebacker Kirk Morrison among others, also shows Kaepernick in the background on one knee.

Kaepernick initially began his protest by sitting during the national anthem during NFL preseason games, citing racial injustice and fatal police shootings in the United States. He has kneeled during the anthem for each of the 49ers' first two regular-season games this season.