Bills fans break into 'USA' chant before Kaepernick's protest

San Francisco 49ers quarterback Colin Kaepernick was booed by the Buffalo Bills' fan base prior to Sunday's game, with a faction breaking into a "USA" chant prior to his protest during the national anthem.

Related: Bills fan tackles dummy dressed as Kaepernick

Kaepernick is kneeling during the national anthem this season as a form of protest against police brutality and racial inequality, and the movement has gained national attention over the past two months.

Related: Cop behind Kaepernick salutes during protest

The quarterback is making his first start of the season, replacing Blaine Gabbert.