A wave of violence erupted during a drought in 1806–7 as tribes in both the north and south of the island killed or wounded several Europeans in conflicts sparked by the competition for game, while explorer and naval officer John Oxley referred in an 1810 report to the "many atrocious cruelties" inflicted on Aboriginal people by convict bushrangers in the north, which in turn led to black attacks on solitary white hunters.[21]