The stunningly powerful female vocals during the middle of "Gimme Shelter," Rolling Stones from "Let It Bleed," they were sung by Merry Clayton, who has been seriously injured in a car accident in California...Merry was one of the singers on Lynyrd Skynryd's "Sweet Home Alabama" too...http://www.rollingstone.com/music/news/gimme-shelter-singer-merry-clayton-seriously-injured-in-car-accident-20140622