SAN FRANCISCO (CBS SF) — A 35-year-old Watsonville man has been arrested on a hate crime charge in the assault of the leader of a weekend conservative free speech rally in San Francisco.

Protest organizer Philip Anderson and others who gathered to demonstrate against Twitter for its policy of policing hate speech and fake political news. Within minutes, there was pushing, shoving and some punches thrown between those protesting and a throng of counter-protester with Anderson getting punched in the face.

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Following the attack, Anderson took the stage at about 1 p.m. and was greeted by chants and plastic water bottles and glass bottles thrown over police barricades.

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In the hours after the assault, San Francisco police investigators developed information that led to the identity of the suspect — Adroa Anderson — who was taken into custody in Oakland on Sunday afternoon.

Police said video and audio evidence indicated that a racial obscenity, consistent with the victim’s ethnicity, was said by the suspect during the assault. Anderson was transported to San Francisco County Jail where he was booked on charges of mayhem and a hate crime enhancement.

Police were also still searching for the suspect or suspects responsible for injuring three SFPD officers, who suffered non-life-threatening injuries when they were assaulted with pepper spray and caustic chemicals.

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While an arrest has been made, this remains an open investigation. Anyone with information is asked to call the SFPD 24 Hour Tip Line at 1-415-575-4444.