A San Francisco 49ers cheerleader took a knee during the national anthem at Thursday night's home game against the Oakland Raiders.

She's believed to be the first NFL cheerleader to join the protest, which was started by Colin Kaepernick when he was playing for the 49ers in 2016.

A San Francisco 49ers cheerleader took a knee during the national anthem at Thursday night's home game against the Oakland Raiders, in what is believed to be the first case of an NFL cheerleader joining the national protest.

Former 49ers quarterback Colin Kaepernick started the movement more than two years ago, when he decided to stay seated during the national anthem to protest racial inequality. He left the team in 2017 to become a free agent and has not been rehired since, which he believes is due to his decision to make a political statement.

The identity of the Gold Rush Squad member who kneeled is still a mystery. Business Insider reached out to the team for comment Friday morning, but has not yet received a response.

—2004 never happened (@GatorLenny) November 2, 2018

Lenny Herrold, a Raiders fan who was seated near the cheerleader and took a picture of the protest up close, spoke to KPIX during the game and said that it was "a cool moment."

"I just thought it was a peaceful, respectful, constitutionally protected free speech," he added.

Herrold said that as soon as he posted the picture, he started getting massive amounts of retweets and replies.

"It's interesting because some people think she's really awesome and other people are like, you should fire her," he said.

The kneeling protests have divided the country, with some believing it's free speech, and others saying that the players are being disrespectful to the nation and the military.

President Donald Trump has been one of the fiercest critics of the protests, at one point calling for owners to fire the players who kneel.

Colin Kaepernick, right, started the protest back in 2016, when he was still a quarterback for the 49ers. AP/Mike McCarn

Most owners appear to agree with Trump, and in May, they passed a new policy whereby teams would be fined for any players who didn't stand for the anthem (players would be allowed to opt out of attending the pregame song by staying in the locker room if they wish). But the players union was highly critical of the policy, and it has been put off for the season while more discussions happen between the unions and the league.

Read more: Trump takes a victory lap after NFL owners cave with new national-anthem rules

Last year, Elle magazine spoke to several NFL cheerleaders to ask why they hadn't joined in on the protests and many expressed fears of losing their jobs.

"Since cheerleaders are often told how replaceable they are, they felt that they could very easily be fired for taking a stand. One pointed out that even a talented, well-known player like Kaepernick essentially lost his job for making a statement. Few cheerleaders would be willing to take that risk," the report found.

Several investigations in recent years, including one in April from The New York Times, have shined a light on the already strenuous and low-paying job of NFL cheerleading, where coaches strictly manage their appearances, how they conduct themselves on social media, and even who they are allowed to socialize with.