LOS ANGELES, June 6 (Reuters) - Helmeted police in riot gear turned out on Friday evening in a tense confrontation with protesters in downtown Los Angeles, after a day of federal immigration raids in which dozens of people across the city were reported to be taken into custody. Live Reuters video showed Los Angeles Police Department officers lined up on a downtown street wielding batons and what appeared to be tear gas rifles, facing off with demonstrators after authorities had ordered crowds of protesters to disperse around nightfall.