4/20 is about peace, love, unity, and smashing someone in the face with an acoustic guitar, apparently.
According to The San Francisco Examiner, the day was relatively peaceful before the fight.
Source: statigr.am
Around 15,000 people attended the event, atop "Hippie Hill," which is the eastern part of Golden Gate Park.
Source: statigr.am
Aside from the massive brawl, the only major complaints were eight arrests for drug sales, six arrests for public intoxication, and around 30 citations for open containers of alcohol.
Source: statigr.am
Also, the excessive littering caused by the crowd cost the city $10,000 and required 4 days of clean-up.
Source: statigr.am
