WILMINGTON, Delaware - When the shots rang out - "pop, pop, pop," and then a thunder roll of gunfire - Maria Williams hit the floor.

The bullets sprayed through her front door and window, leaving perfectly cylindrical holes in the glass. They blasted across the nursery, where her 2-year-old daughter's toys were strewn on the carpet. They burrowed into the kitchen cabinetry - and hit her teenage son and daughter.

Amid their screams, "All I could think of was, 'I'm not losing another child,'" Williams recalled, tears streaming down her cheek.

Her 18-year-old stepson - William Rollins VI, known as Lil Bill - had been gunned down two years before, another victim of Wilmington's plague of teens shooting teens. His shooter was 17.

Wilmington isn't Chicago or Los Angeles, Baltimore or Detroit. It is a city of less than 72,000 people known primarily as the birthplace of chemical giant DuPont and as a cozy home for big banks and Fortune 500 firms. But an Associated Press and USA TODAY Network analysis of Gun Violence Archive data - gathered from media reports and police press releases, and covering a 3½ year period through June of this year - reveals that Wilmington far and away leads the country in its rate of shootings among young people ages 12 to 17.

"It's nonstop, just nonstop," said William Rollins V, father of the teenagers. "Around every turn, they're taking our kids."

Of the 10 cities with the highest rates of teen shootings, most had populations of less than 250,000 people. Among them were Savannah, Georgia; Trenton, New Jersey; Syracuse, New York; Fort Myers, Florida; and Richmond, Virginia. Chicago was the lone large-population city high on the list.

Poverty and a sense of hopelessness in the most violent neighborhoods is a common thread. Syracuse, a university town that once cranked out air conditioners and televisions, now has a poverty rate of 35 percent.

Others, like Savannah, are deeply divided. While its antebellum mansions, gnarled live oaks and marble monuments to war heroes drew more than 13 million visitors last year, away from picture-postcard oasis of Southern Charm the scenery here quickly shifts to decaying neighborhoods, abject poverty and deadly violence.

Size may play a role. In tightly packed neighborhoods, insults and perceived insults ricochet like shots in an echo chamber. One shooting inevitably leads to speculation about who will be targeted next.

"The streets remember," said Mark Denney, a state prosecutor who is trying to end Wilmington's retaliatory warfare.

Social media accelerates the threats, and the danger. Teenagers whose brains are years from fully maturing are roaming the streets with a gun in one pocket and a smartphone in the other.

"A juvenile with a gun is a heck of a lot more dangerous than a 24- or 25-year-old with a gun," said James Durham, the acting U.S. attorney based in Savannah.

During a recent presentation, Chaz Mollins, coordinator of violence prevention programs for Christiana Care Health System in Wilmington, showed a group of teens a map of Wilmington studded with pushpins, each marking the location of a shooting: white for injuries, red for homicides.

The pins, clustered in a handful of high-poverty neighborhoods, showed the kind of pattern you might see in an outbreak of some infectious disease, like Zika or Ebola, Mollins said.

"So," he said, "we are in the midst of an epidemic."

The problem facing Wilmington and these other cities: How to stop the spread?

For Malik Walker, the best thing about turning 18 wasn't the birthday party he threw for himself at a local hotel. It's the fact that, as an adult, he can now legally buy a gun.

Malik was just 12 when he dodged his first shootout on Wilmington's notorious west side. At 15, he was kneeling on a sidewalk, calling an ambulance as he pressed his shirt against his best friend's bloody chest. The friend had been shot 13 times on the corner where Malik had just been standing.

Three years later, the tall, slender teenager with an easy smile still shudders at the thought that, had he not stopped into a store for a juice, he could have been lying there, too.

"I'm scared to even tie my shoe, because I don't know who might creep up behind me," Malik said as a police car's strobing red-and-blue lights illuminate the unfurnished room where he and several friends have gathered on a sticky, summer night. "It makes me want to take these two eyes and make two more, and put them in the back of my head."

For teens in the First State's largest city, this is life.

In Wilmington, data from the Gun Violence Archive show that roughly 3 out of every 1,000 adolescents are injured or killed annually from gun violence. That is almost twice the rate reported from Chicago and just over 9 times the national average as reported for 2015 by the U.S. Centers for Disease Control and Prevention.

The news organizations sought to measure teenage gun violence in America's cities because it is something the federal government does not track on a regular and comprehensive basis.

Nearly a quarter of Wilmington's residents live below the poverty line. Eighty-six percent of the city's youth receive some form of state assistance.

Single-parent families live packed together in old-style housing projects or dilapidated brick row houses. Already separated from the more prosperous parts of town, Wilmington's poorer and largely black neighborhoods are divided physically by Interstate 95, which bisects the city, and by cliques that carve those neighborhoods into rival sections: Hilltop and West Center City; "The Hill" and "Down Bottom."

About 30 active street crews exist in Wilmington today, estimated David Kennedy, a national expert in criminology who has for years studied the city's crime problem. Prosecutors say these crews, made up of roughly 20 people per group, are responsible for most of Wilmington's crime.

A yearlong investigation by The News Journal, Gannett's Wilmington newspaper that is part of the USA TODAY Network, detailed a veritable war between two groups - Only My Brothers and Shoot to Kill. A News Journal analysis of court records, social media and the newspaper's internal database found that a third of the shooting victims under age 21 during the first seven months of 2016 had links to the rivalry.

The feud began in January 2015 with the death of 16-year-old Jordan Ellerbe, gunned down while listening to music with friends on a front porch in the city's Hilltop neighborhood. The same home was targeted again two days later, leaving three mourners wounded.

The war escalated in the months that followed. One gang member would shoot at a rival; weeks later, fire would be returned. In May 2016, 15-year-old Brandon Wingo was shot and killed on his way home from school.

A month later, three alleged members of Shoot to Kill were charged with the popular basketball player's death. Between July and September of 2016, officials arrested 28 alleged OMB members on charges of gang participation, carrying concealed guns, robbery and attempted assault. An additional teen was later charged as part of OMB, bringing the total to 29.

Robert Tracy, Wilmington's new police chief, says the city needs to do more of this - identifying those committing crimes and getting them off the street. It's a strategy employed in other cities.

"There's a small percentage of individuals that are going back and forth causing this violence in the city," Tracy, Chicago's former top crime strategist, said earlier this year during a vigil for a 6-year-old boy who had been shot. "And all the good people are tired of it, and they're outraged."

Unlike larger, more organized criminal enterprises such as the Crips, the Bloods or the Mexican Mafia, feuds among teenage gangs in Wilmington don't revolve around drugs, or territory, or even money. It's about respect.

In the internet age, bad blood can spring up and spread instantly online with the double tap of a thumb on a smartphone screen or a hastily tapped-out Tweet. Teenagers in Wilmington don't sport gang colors or uniforms, but identify themselves with emojis and hashtags.

"Technology's evolution has made it easier for criminals to get guns," said Deputy Attorney General Joseph Grubb. "It also has made it easier for young people to get offended by something, causing them to go grab a gun and shoot up a block as opposed to, 'Meet me in the school yard and let's fist fight.'"

And every shooting opens up the possibility for another, as the thirst for retaliation creates a bloody game of back-and-forth: a life for a life for a life. According to Centers for Disease Control and Prevention research, young men under the age of 34 who have been shot in Wilmington are 11 times more likely to commit gun violence in their lifetimes.

Mayor Mike Purzycki said some of the blame can be laid on a "fractured education system" that sends children on buses to schools in rival neighborhoods. Many fathers are either in prison or have past convictions that make it difficult for them to find good jobs.

All of this leads to hopelessness and powerlessness, said the Rev. Derrick Johnson of the Joshua Harvest Church. "Pastor D," as he's known on the streets, understands that feeling, because he too has been there. Johnson was a 17-year-old drug dealer when he fatally shot a man. He was freed after serving 15 years.

At 59, Johnson's ministry is as much in the streets as it is in the pulpit.

One afternoon, Johnson strolled down the stairs of the William "Hicks" Anderson Community Center in the city's troubled West Center City neighborhood. A group of little girls, licking Popsicles, stood on the landing, leaning against the railing and peering down at the pastor. He reached into his pocket and handed each child a dollar bill.

"What you be doing when they be shooting around here?" he asked the children.

"Running home," said a girl with pigtails.

"You run?" the minister said, "you're supposed to duck."

"I learned that in school," another girl shouts. "I duck my head, somewhere where they won't find me."

William Rollins and Maria Williams believe the attack on their home can be traced back to the death of Lil Bill, in January 2015. In its aftermath, Rollins had received chilling text messages with photographs of his youngest son, just 11 at the time. "Should he be next?" the sender asked. Other threats in texts and on social media followed.

On July 21, John Brisco, aka "Bin Laden," was given two life sentences in Lil Bill's murder. So notorious is the Touch Money Crew gangster in the Hilltop neighborhood that "Osama City" was scrawled in Sharpie on the wall of a liquor store. "Love you, Osama," said another tag; and another, #LongliveOsama.

On July 26, the Rollins' home came under fire.

After the children were released from the hospital, the family left Wilmington. On a recent afternoon, 16-year-old Keshon and 18-year-old Kieshonna sat on a picnic bench beneath a shade tree. Kieshonna unwrapped the bandage from her knee to reveal an angry inch-wide gash just below her kneecap; Keshon's wounds had scabbed over.

The teenagers want to return to Wilmington, but their parents will have none of that world.

"The craziest thing about it is, these kids are accepting it," William Rollins said. "Like, they're accepting going to jail for life. They're accepting getting put in the grave. But they don't realize the effect that they do to everybody else around them."

To his wife, gun violence among teenagers has simply become part of everyday life in Wilmington: "Somebody taking somebody's child's life, over nothing." - AP