Attorney General Eric Holder summoned several of the nations chiefs of police to Washington this week to seek their input on an alarming spike in police fatalities.

For the two years before 2010, shootings of police officers had been on the decline. But that changed last year.

Department of Justice figures for that year show officer deaths jumped 40 percent, with firearm fatalities climbing by nearly 25 percent.

And the trend appears to be more than an anomaly.

"This year we are unfortunately on track to exceed the numbers we saw last year," Holder told the assembled chiefs. "We are already three full months into 2011 and yet we have already lost 48 law enforcement officers."

Holder's comments echoed a police shooting incident this week in Athens, Ga., where authorities say an officer was allegedly shot and killed while he tried to apprehend a suspect.

There is no shortage of speculation about what's causing the spike but there are also no hard answers. Just as troubling is the fact that the jump is occurring as the rate of violent crime and murder in the general population is declining.

"It's not any one thing," says Chief Cathy Lanier of the Washington, D.C., Police Department. "We see repeat violent gun offenders who are involved in these officers killed in the line of duty. We also see people with mental health issues."

Holder is calling on U.S. attorneys around the country to convene sessions with local law enforcement officers, seeking ways to combat the upsurge in violence. Some say that the routine and oft-heard calls to better equip police departments to battle increasingly well-armed thugs, may not be an effective solution.

"We're not seeing AK-47's, and we're not seeing high-capacity magazines," Baltimore Police Chief Fred Bealefeld said.

Some speculate that a combination of factors may be contributing to the uptick in cop shootings, including economic stresses, mental illness, drug use and alcoholism andlax sentencing of violent offenders, as well as a host of other socio-economic pathologies.

Officers have long been aware of the endemic distrust, fear and even hatred of police in some communities. Some fear the spike in violence may reflect a partial mainstreaming of that dysfunction.