All offenses in the violent crime category, including murder, rape, aggravated assault and robbery, showed decreases in the first six months of 2014 compared to the same period in 2013, the FBI report says. 

Tennessee topped the list of the FBI's rankings of states with violent crime, followed by Nevada and Alaska. While these rankings do not account for many different factors – grouping crime by state can be simplistic and ignore factors that influence crime, the FBI warns – many states with the highest and lowest rates have remained consistent for many years. 

The number of violent crimes, however, increased 0.7 percent in 2012, with an estimated 1,214,462 violent crimes. 

Four of the top 10 most dangerous neighborhoods are located in Detroit, where there is a high number of vacant residences and empty lots.

The first six months of 2012 showed a 1.9 percent increase in violent crime, and a 1.5 percent increase in property crime. 

Most active shooters in the past decade acted alone, the report notes, and 51 percent were deceased following the attack. 

New reports from the FBI show a 6 percent decrease in hate crime in 2011, but not all states are participating in the data collection effort. 

A 4 percent drop in overall violent crime is reported in the FBI Uniform Crime Report for 2011.

There were nearly 600 fewer instances of bank crime in 2011 than 2010, according to the most recent report from the FBI.

Seventy-two officers were feloniously killed in the line of duty during 2011, according to preliminary statistics from an FBI report.