Six people buried in a single grave in Latvia more than 1,000 years ago may have been killed in a bloody Viking raid, a new study suggests.Genetic research into the deceased — four men, a boy and a girl — reveals family connections: The boy was the son of one of the men, while another man was a third-degree relative, perhaps a first cousin or great uncle, the researchers found.The father, the relative, and one other man died from "sharp force" injuries — maybe wounds from an ax or a sword; but it's unknown how the other three individuals died, the researchers reported in the study, which was published in the September issue of the Journal of Archaeological Science: Reports. One possibility i...