Robberies, shootings, and homicides are up this year, but Rochester Police Chief Jim Sheppard, who gave his mid-year crime report this afternoon, says the public should consider the historical context.

Violent crime, which includes murder, rape, robbery, and aggravated assault, is up 4.8 percent from this time last year, from 904 to 947 incidents. Murders rose from 14 to 20; rape, 41 to 46; and robbery, 310 to 366. The only category of violent crime to see a decline is aggravated assault, which dropped from 539 to 515.

The five-year averages for violent crime are as follows: murder, 19; rape, 45; robbery, 467; and aggravated assault, 522.

For the first half of this year, Rochester has had 95 shootings. That’s an increase from 55 shootings in the same period in 2011. Previous-year totals: 2010, 87; 2009, 47; 2008, 83. Over the last decade, the worst half-year for shootings was 2006, with 119.

Sheppard said that loosely affiliated gangs are behind many of the shootings. A particular group in northeast Rochester, known to frequent the Carter-Roycroft area, is responsible for 15 to 20 of the shootings, Deputy Chief Mike Wood said. And that’s not counting incidents where group members were shot at, he said.

Wood said that the RPD recently arrested some of the group’s “main players,” and that more arrests are anticipated.

Chief Sheppard said he is in discussions with a group to start a gun buy-back program. He said the guns that people turn in through these kinds of programs aren’t usually the ones causing the trouble, but that he’s game to try everything. He wouldn’t name the group he’s negotiating with.