(CNN) Four teenage girls have been arrested for the alleged beating of a 15-year-old girl who authorities say has special needs. The beating was captured in a viral video that's been viewed millions of times.

Two of the arrested suspects are 15 years old, police said. The others are 13 and 14 years old.

Three of the suspects face charges of aggravated battery, and one faces a charge of mob action, police said.

The girl who appears in the video had been reported missing on July 18, Lt. Ozzie Valdez told reporters Thursday. At the time she was reported missing, police were unaware of the viral video, which was posted to Twitter on Monday.

Police said that community activists first drew their attention to the 42-second video.

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