At least one person was arrested during an early morning raid of the San Francisco headquarters of the Hells Angels motorcycle gang, SF police say.

At 5 AM, SFPD officers served a search warrant on the "Frisco" (their word choice, not ours) Angels outpost at Tennessee and 23rd Street in Dogpatch, according to SFPD spokesperson Officer Albie Esparza.

According to KTVU, SWAT team members and a drug-sniffing dog accompanied the SFPD's Gang Task Force members as they blocked off area streets and stormed the club.

Though Esparza remained cagey on the reason behind the search (see update below), saying only that "members of the media can contact SF Superior Courts for the affidavit and obtain details in regards to the search warrant service," SFPD chief Greg Suhr told KCBS that the warrant involved "an investigation into a felony aggravated assault."

According to Esparza, one person was arrested and taken into custody during the sweep.

Update: According to Esparza, 42-year-old SF man Charles Nucci (photo above) was this morning's arrestee, and was booked into San Francisco County Jail on aggravated assault related charges. Police say that they believe Nucci was a participant in a 2013 attack in which "several suspects wearing Hells Angels jackets assaulted an individual in San Francisco," leaving the victim with serious injuries.

According to Chief Deputy Sheriff Kathy Gorwood, Nucci was released on $175,000 bond this afternoon.

The San Francisco chapter of the notorious motorcycle club is reportedly the second-oldest Hells Angels club in the country. The Frisco sect is no stranger to the law, and was subject to a federal investigation in July 2008. In that same year, then-chapter president Mark "Papa" Guardado was shot and killed at 24th Street and Treat Avenue, in what was believed to be a dispute with a rival motorcycle gang.