The summer of 2012 was a dangerous one on Bloomington’s streets as clusters of teens picked up handguns and went outside to settle disputes with rivals who also had access to bullets and weapons.The groups identified by police as “hybrid gangs” accounted for 14 shootings that year, including several that left people injured. The escalation of gun violence led police to develop new strategies, said Jack McQueen, supervisor of the Bloomington Police Department’s crime and intelligence analysis unit.The 2012 conviction of …