“Bellatrix was still fighting too, fifty yards away from Voldemort, and like her master she dueled three at once: Hermione, Ginny, and Luna, all battling their hardest, but Bellatrix was equal to them, and Harry’s attention was diverted as a Killing Curse shot so close to Ginny that she missed death by an inch–
He changed course, running at Bellatrix rather than at Voldemort, but before he had gone a few steps he was knocked sideways.
‘NOT MY DAUGHTER, YOU BITCH!’
Mrs. Weasley threw off her cloak as she ran, freeing her arms. Bellatrix spun on the spot, roaring with laughter at the sight of her new challenger.
‘OUT OF MY WAY!’ shouted Mrs. Weasley to the three girls, and with a swipe of her wand she began to duel. Harry watched with terror and elation as Molly Weasley’s wand slashed and twirled, and Bellatrix Lestrange’s smile faltered and became a snarl. Jets of light flew from both wands, the floor around the witches’ feet became hot and cracked; both women were fighting to kill.”
-J.K. Rowling, Harry Potter and the Deathly Hallows, pages 735-736