Facebook has apologized for censoring an activist for Black Lives Matter.

Shaun King, who is also a New York Daily News writer, was blocked from the social network after posting a screenshot of a racist email he received in which the sender harassed him using explosive profanity and twice referring to him as the “N-word.” King was then informed that his post had been removed from the site, and he received a 24-hour ban from posting anything else.

The ban didn’t last that long. King, who the Guardian writes was a guest speaker at Facebook fb earlier this year to talk about the Black Lives Matter movement, reached out to his connections at the social media company and was able to restore his access after about six hours. He received a response saying, “This was a mistake, and we sincerely apologize for the error.”

 

In a follow-up post, King wrote that he’s heard of similar things happening to others—”SO many of you have told me that you have had your accounts suspended for FIGHTING BIGOTRY while the bigots often seem to be able to say whatever the hell they want.”

“The post was removed—and profile suspended—in error and restored as soon as we were able to investigate,” Facebook told Fortune in a statement. “Our team processes millions of reports each week, and we sometimes get things wrong. We’re very sorry about this mistake.”

King’s post was originally removed for violating “community standards,” which a Facebook spokesperson later told the Guardian that it did not. The site’s community standards specifically acknowledge that some users may “share content containing someone else’s hate speech for the purpose of raising awareness or educating others about that hate speech,” though they should “clearly indicate their purpose” to help Facebook understand why they shared it.

Just a few days ago the social network was criticized for removing an iconic photo from the Vietnam War. Though Facebook rejects the idea that it’s a media company, critics argue that it does have the same responsibilities as one. Because many users rely on the platform for their daily news, some experts say that Facebook should hire editors qualified to distinguish between hate speech and what the site calls “content containing some else’s hate speech for the purpose of raising awareness.”