Story highlights Video shows man's wrists bound as people kick and punch him

The suspects, two men and two women, are in custody awaiting formal charges

(CNN) A young woman who broadcast the beating and racial taunting of a man on Facebook Live has been arrested with three others in connection with the gruesome attack, Chicago police said Wednesday.

The disturbing 30-minute video shows a man tied up and his mouth covered, cowering in the corner of a room. His attackers laugh and shout "f*ck Donald Trump" and "f*ck white people" as they kick and punch him.

The video shows someone cutting into his scalp with a knife, leaving a visibly bald patch.

Police said the victim is an 18-year-old with special needs. Officers found the disoriented young man wandering a Chicago street "in crisis" Tuesday afternoon.

He was so traumatized that it took most of the night for him to calm down so he was able to talk to police, Capt. Steven Sesso said.

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