This can be stated in active form. Alternate translation: "For they slaughtered you" or "For people killed you" (See: [[rc://en/ta/man/jit/figs-activepassive]])
Since blood represents a person's life, losing the blood represents dying. This probably means "by your death" or "by dying." (See: [[rc://en/ta/man/jit/figs-metonymy]])