CHICAGO (AP) — States with the most gun control laws have the fewest gun-related deaths, according to a study that suggests sheer quantity of measures might make a difference.

But the research leaves many questions unanswered and won't settle the debate over how policymakers should respond to recent high-profile acts of gun violence.

In the dozen or so states with the most gun control-related laws, far fewer people were shot to death or killed themselves with guns than in the states with the fewest laws, the study found. Overall, states with the most laws had a 42 percent lower gun death rate than states with the least number of laws.

The results are based on an analysis of 2007-2010 gun-related homicides and suicides from the federal Centers for Disease Control and Prevention. The researchers also used data on gun control measures in all 50 states compiled by the Brady Center to Prevent Gun Violence, a well-known gun control advocacy group. They compared states by dividing them into four equal-sized groups according to the number of gun laws.

The results were published online Wednesday in the medical journal JAMA Internal Medicine.

More than 30,000 people nationwide die from guns every year nationwide, and there's evidence that gun-related violent crime rates have increased since 2008, a journal editorial noted.

During the four-years studied, there were nearly 122,000 gun deaths, 60 percent of them suicides.

"Our motivation was really to understand what are the interventions that can be done to reduce firearm mortality," said Dr. Eric Fleegler, the study's lead author and an emergency department pediatrician and researcher at Boston Children's Hospital.

He said his study suggests but doesn't prove that gun laws — or something else — led to fewer gun deaths.

Fleegler is also among hundreds of doctors who have signed a petition urging President Barack Obama and Congress to pass gun safety legislation, a campaign organized by the advocacy group Doctors for America.

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Gun rights advocates have argued that strict gun laws have failed to curb high murder rates in some cities, including Chicago and Washington, D.C. Fleegler said his study didn't examine city-level laws, while gun control advocates have said local laws aren't as effective when neighboring states have lax laws.

Previous research on the effectiveness of gun laws has had mixed results, and it's a "very challenging" area to study, said Dr. Daniel Webster, director of the Johns Hopkins Center For Gun Policy. He was not involved in the current study.

The strongest kind of research would require comparisons between states that have dissimilar gun laws but otherwise are nearly identical, "but there isn't a super nice twin for New Jersey," for example, a state with strict gun laws, Webster noted.

Fleegler said his study's conclusions took into account factors also linked with gun violence, including poverty, education levels and race, which vary among the states.

The average annual gun death rate ranged from almost 3 per 100,000 in Hawaii to 18 per 100,000 in Louisiana. Hawaii had 16 gun laws, and along with New Jersey, New York and Massachusetts was among states with the most laws and fewest deaths. States with the fewest laws and most deaths included Alaska, Kentucky, Louisiana and Oklahoma.

But there were outliers: South Dakota, for example, had just two guns laws but few deaths.

Editorial author Dr. Garen Wintemute, director the Violence Prevention Research Program at the University of California, Davis, said the study doesn't answer which laws, if any, work.

Wintemute said it's likely that gun control measures are more readily enacted in states with few gun owners — a factor that might have more influence on gun deaths than the number of laws.

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Online:

JAMA Internal Medicine: http://www.jamainternalmed.com

CDC: http://www.cdc.gov

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AP Medical Writer Lindsey Tanner can be reached at http://www.twitter.com