Counting all violent deaths -- murder, manslaughter and people killed by the police -- the number for January to June hit 3,001, up from 2,553 during the same period in 2015, the Institute for Public Security said.
The figures covered the whole state of Rio, although the vast bulk of incidents are in the city of Rio and its suburbs, where some 500,000 tourists are expected for the Olympics starting August 5.
The number of deaths as a result of police action -- a closely watched statistic in a city where police violence is notorious -- reached 399 for January to June, up 14.3 per cent from last year.
The number of deaths of police officers was steady at 15, down one from the first half of last year.
Street robberies rocketed, up 34 percent to 58,999 incidents.
The bright side of the generally dark scenario was that murders are well off their peak in April when there were 471 killings, compared to 376 in June.
Brazil has deployed tens of thousands of soldiers and extra police to Rio to help with security during the Olympics.