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San Francisco 49ers quarterback Colin Kaepernick continued to protest how people of color are treated in the United States on Sunday, kneeling during the national anthem ahead of his team's Week 2 game against the Carolina Panthers, per Marcus Thompson of the Bay Area News Group.

Teammate Eric Reid joined Kaepernick as well. According to the Sacramento Bee's Matt Barrows, safeties Jaquiski Tartt and Antoine Bethea and linebacker Eli Harold held their fists up.

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Before the Miami Dolphins took on the New England Patriots, Dolphins running back Arian Foster knelt during the anthem, repeating his protest from last week, per the Palm Beach Post's Joe Schad.

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Kaepernick's protest began in the preseason and gained nationwide attention when he sat on the bench as "The Star-Spangled Banner" played before San Francisco's 21-10 loss to the Green Bay Packers on Aug. 26. He discussed the aims of his protest with NFL Media's Steve Wyche:

I am not going to stand up to show pride in a flag for a country that oppresses black people and people of color. To me, this is bigger than football and it would be selfish on my part to look the other way. There are bodies in the street and people getting paid leave and getting away with murder.

On Sept. 6, ESPN.com's Nick Wagoner reported Reid suggested Kaepernick start taking a knee instead after the duo talked about the issue with Nate Boyer, a former Green Beret and NFL long snapper.

Foster and other Dolphins players joined Kaepernick and Reid in Week 1, which coincided with the 15th anniversary of the Sept. 11, 2001, terrorist attacks. The running back tweeted a response to those criticizing the timing of his protest:

Foster told ESPN.com's James Walker he doesn't intend to stop the demonstration anytime soon. The Miami Herald's Armando Salguero reported Jeff Bell, the president of the Broward County Sheriff's Office Deputies Association, asked officers to decline to provide security and escorts for Dolphins players because of the protest.

Denver Broncos linebacker Brandon Marshall again took a knee during the anthem prior to his team's game against the Indianapolis Colts, per Mike Klis of 9News.

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Before the Seattle Seahawks played the Los Angeles Rams, Gregg Bell of the News Tribune reported head coach Pete Carroll stood with his players as they locked arms during the anthem.

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The movement has grown beyond the NFL. United States women's national soccer team star Megan Rapinoe took a knee as the anthem played before an international friendly against Thailand on Thursday. On Friday, the entire football team from Garfield High School in Seattle knelt ahead of its game against West Seattle High School.

"Everybody wants to talk about how this is disrespectful to the American flag," Garfield head coach Joey Thomas said, per the Seattle Times' Jayda Evans. "That's a smokescreen. How about we talk about the issues people are kneeling and fighting for? If we could start addressing the issues and finding solutions to the issues, we won't have to kneel."