Reports of violent crime, including homicide, rape, robbery and aggravated assault, declined by 6.4 percent during the first six months of this year compared to the same time frame in 2010, according to the FBI.

The FBI's Preliminary Semiannual Uniform Crime Report also showed that property crimes decreased by 3.7 percent.

The report is based on information from more than 12,500 law enforcement agencies that submitted three to six comparable months of data to the FBI in the first six months of 2010 and 2011.

Murders declined by 5.7 percent; rapes by 5.1 percent; robbery by 7.7 percent and aggravated assault by 5.9 percent.

Law enforcement agencies in all of the city population groups reported decreases in violent crime. Cities with populations of 50,000 to 99,999 recorded the largest decrease in violent crime at 7.2 percent. Violent crime also declined in metropolitan counties by 7.6 percent and in nonmetropolitan counties by 6.4 percent.

Violent crime declined in each of the nation's four regions. The largest decrease, 9.7 percent, was in the Midwest, followed by 6.6 percent in the West, 5.8 percent in the South, and 3.6 percent in the Northeast.

All three categories of property crime -- burglary, larceny-theft and motor vehicle theft -- also showed declines. Burglary offenses declined 2.2 percent, larceny-theft dropped by 4 percent and motor vehicle theft fell by 5 percent.

Law enforcement agencies in cities with populations of 100,000 to 249,999 inhabitants reported the largest drop in property crimes at 5.1 percent. Property crime in metropolitan counties declined 3.2 percent; property crime in nonmetropolitan counties decreased 0.5 percent.

Each region reported declines in the number of property crime: 4.4 percent in the Midwest, 4.0 percent in the West, 3.8 percent in the Northeast, and 3.0 percent in the South.

Arsons declined by 8.6 percent overall. In the Northeast, arsons declined by 14.5 percent; 8.8 percent in the Midwest; 7.8 percent in the West and 7 percent in the South. The number of arsons also fell in all population groups. Cities with populations of 100,000 to 249,999 reported the largest decrease of 13.5 percent.