Violent crime increased last year, and many cities experienced double-digit or even triple-digit percentage increases in homicides and other violence, according to the latest statistics gathered by the Police Executive Research Forum (PERF), a Washington, D.C.-based organization of police chiefs, sheriffs, and other state and local law enforcement leaders.

The PERF report says that the organization gathered crime statistics for 2006 from 56 police agencies nationwide and found that overall, homicides increased 2.89 percent compared to 2005, and robberies increased 6.48 percent. Aggravated assaults declined 2.20 percent, but when aggravated assaults committed with a firearm were separated out of that category, there was a 1.28-percent increase between 2005 and 2006.

PERF says the findings are "not uniformly discouraging." Dallas, Denver, and Washington, D.C., for example, reduced their homicide tolls significantly. Some cities experienced increases in certain types of violent crime but not in others.

But overall, PERF says the 24-month trend, starting on Jan. 1, 2005, is unmistakable. Among the jurisdictions filing reports with PERF, total homicides in 2006 were 10.21 percent higher than they were in 2004. Robberies increased 12.27 percent; aggravated assaults increased 3.12 percent; and aggravated assaults with a firearm increased 9.98 percent.

The report shows that major increases in violence are not limited to a few cities. Some 75 percent of PERF's 56 jurisdictions reported increases in robberies between 2005 and 2006.

Here are some of the findings of the report:

¥ Homicides increased more than 20 percent or more over the two years in Baltimore County, Md., Boston, Charleston, S.C., Charlotte-Mecklenburg, Cincinnati, Cleveland, Fairfax County, Va., Hartford, Conn., Kansas City, Mo., Memphis, Nashville, Newark, New Haven, Conn., Orlando, Philadelphia, Rochester, N.Y., San Antonio, San Jose, and Seattle.

¥ Robberies increased more than 30 percent between 2004 and 2006 in Arlington, Texas, Baltimore County, Md., Cleveland, Detroit, Fort Wayne, Ind., Las Vegas, Memphis, Milwaukee, Minneapolis, Montgomery County, Md., Orlando, Prince William County, Va., Rochester, N.Y., San Francisco, San Jose, and Virginia Beach.

¥ Aggravated assaults with firearms increased more than 30 percent over the two years in Boston, Cincinnati, Cleveland, Las Vegas, Orlando, Rochester, N.Y., Sacramento, St. Louis, Seattle, and other jurisdictions.

¥ Homicides fell in Atlanta to a total of 112 in 2004 to 89 in 2005, but jumped to 107 in 2006.

PERF says its findings are disturbing because the U.S. experienced declines in crime during the mid- to late-1990s, followed by a leveling off in the early 2000s.

The reasons for the nationwide increase in crime have been attributed to budget cuts, fewer police on patrol, more people in poverty, gang violence, gun laws, and a preoccupation of American law enforcement with the threat of foreign terrorism.