SAN FRANCISCO—A mountain lion that attacked a 5-year-old boy and dragged the child across his front lawn in Southern California was shot and killed by a wildlife officer, authorities said Saturday. The 65-pound mountain lion attacked the boy while he was playing near his house Thursday in Calabasas and “dragged him about 45 yards” across the front lawn, said Capt. Patrick Foy, a spokesman with the California Department of Fish and Wildlife. The boy suffered significant traumatic injuries to his head and upper torso but was in stable condition at a Los Angeles hospital, Foy said. “The true hero of this story is his mom because she absolutely saved her son’s life,” Foy said. The mother was inside the house when she heard a commotion outside. “She ran out of the house and started punching and striking the mountain lion with her bare hands and got him off her son,” …