DECIMATE!
"USAGE NOTE Decimate originally referred to the killing of every tenth person, a punishment used in the Roman army for mutinous legions. Today this meaning is commonly extended to include the killing of any large proportion of a group. Sixty-six percent of the Usage Panel accepts this extension in the sentence The Jewish population of Germany was decimated by the war, even though it is common knowledge that the number of Jews killed was much greater than a tenth of the original population. However, when the meaning is further extended to include large-scale destruction other than killing, as in The supply of fresh produce was decimated by the nuclear accident at Chernobyl, only 26 percent of the Panel accepts the usage."
From the American Heritage Dictionary. Seen here.