15 shot after a ‘sideshow’ took over a peaceful Juneteenth celebration in Oakland, police say

OAKLAND, Calif. — Fifteen people were shot after an illegal “sideshow” took over a peaceful Juneteenth celebration in Oakland, California, police said Thursday.Investigators are seeking multiple shooters — more than 50 shell casings were recovered at the scene — following the violence Wednesday night at Lake Merritt, but no arrests had been made by Thursday afternoon.About 20 vehicles — mostly all-terrain vehicles and dirt bikes — arrived around 8:15 p.m. Wednesday and started a…