On Wednesday, two Philadelphia teens, ages 16 and 17, were wounded in separate shootings, the latest in a bleak trend quantified in a new analysis from Yale University. Examining data from thousands of hospital visits, researchers found that more than three-quarters of children admitted into U.S. hospitals with gunshot wounds in recent years were city kids aged 15 to 19.

In fact, the rate of firearm injury due to assault was nearly eight times higher among urban versus rural teens. Overall, counting accidental injury, urban teens suffered a nearly three-times-higher rate of gun injuries.

But for their little brothers and sisters, gun risks are different, researchers reported. Preteens in rural communities suffered a 48 percent higher rate of accidental gun injury.

Meanwhile, the rate of self-inflicted firearm injuries was highest among rural teenagers — a trend that has been noted before. Experts cite increased access to firearms and reduced access to mental -health services as part of the cause.

Gun violence is now a leading cause of pediatric injury and death in the U.S., with 13,723 children surviving firearms injuries in 2015. Nearly 3,000 kids died of gun violence that year.

The Yale study examined data from thousands of U.S. hospital visits in 44 states during 2006, 2009 and 2012. It was among the first to look at the urban-versus-rural divide in pediatric gun injuries.

The findings make sense to University of Pennsylvania criminologist John MacDonald, who wasn't involved in the study. "Kids are more exposed to long guns and shooting for sport and hunting in rural areas — and accidents happen. In urban areas, gun-related injuries tend to be more intentional," he said.

MacDonald said Philadelphia is one of the more dangerous cities in the country in terms of risks of gun-related injuries and fatalities.

According to federal data, Philadelphia County saw more than 40 percent of Pennsylvania's firearm deaths in 2014 (532 out of 1,217). Yet just an eighth of the state's population lives here. Pennsylvania's rate of firearms mortality is higher than in neighboring states and slightly higher than the national average. Between 2005 and 2014, more than twice as many Pennsylvanians were killed by firearms than American soldiers were lost in Afghanistan and Iraq.

MacDonald said the new study's focus on regional variations is important because the topic has so far been understudied and underappreciated.

"There isn't going to be one policy that fits this problem," he said. Solutions need to be tailored. "There should be a stronger emphasis on gun safety and also storage [in rural communities]. I'm sure a lot of these [cases] are kids getting ahold of guns when they are not being supervised." For urban shootings, "you want to focus on why people are carrying illegally or even legally that could lead to cases of violence."

The Yale team analyzed the Kids' Inpatient Database, a product of a federal, state and industry partnership aimed at improving health care across the country. Each patient was classified according to county of residence; those with more than 50,000 people were classified as urban, those with fewer than 10,000 people were considered rural.

Because the study relied on hospitalization records, children killed by firearms who were never taken to a hospital were not included in the analysis. Similarly, classifications of assault, accidental discharge, and self-inflicted firearm injury were drawn from hospital records, which may contain misclassifications.

The database also did not include gun-related injuries that were serious enough to send kids to the emergency room but did not require admission into a hospital. "[Unintentional injuries] are probably even higher in rural areas than are being picked up — grazed by a bullet, or something like that," said MacDonald.

Despite the limitations of the study, it provides hard data on gun violence to help inform debate over gun policy, MacDonald said. "[It] can highlight that this isn't just one person's opinion or a group of people's opinions. There's a pattern here, and there is a public-health issue."