At 10:45 on the night of March 13, 2009, Rodney Orange waited for his 14-year-old grandson, Gregory Robinson, to arrive home. Gregory had been at a high school basketball game, and as the car he rode in pulled up outside the house, Mr. Orange heard the sound of semi-automatic weapons. He remembers two distinct sounds of gunfire, suggesting there were two shooters. More than 50 shots were fired. He rushed to the car. Gregory had been sitting in the backseat and had thrown his body on top of his two younger cousins, one five years old, the other nine months. He saved their lives. Gregory was shot in the back.

“He wasn’t responding to me,” Mr. Orange recalled. “It was like he was saying, ‘I’m OK, but this is hurting.’ That’s the way he was. He wouldn’t scream and holler. But it hurt. It hurt so bad.” When Mr. Orange, a dignified, stolid man, related this story, it was clear he was talking both about himself and his grandson. Gregory died later that night.

Gregory Robinson’s burial is the opening scene of The Interrupters, the film I made with my longtime friend Steve James, and I tell the story of Gregory’s family because it speaks to the profound, unrelenting pain of losing someone to the streets. When we met up with Mr. Orange and his daughter, Gregory’s mom, it had been seven months since the murder, but their grief felt fresh and raw, as if it had happened the previous day. Gregory’s mother, Dawn, hadn’t touched her son’s bedroom. It was just as Gregory left it, his slippers at the foot of his bed. His basketball — he’d just made his high school freshman team — balanced precariously on the dresser. On a shelf in his closet, Dawn had left untouched Gregory’s collection of M&M dispensers.

Dawn so deeply grieved, she’d been unable to return to her job at the Chicago Transit Authority. “I have my days,” she told us. “I’m not always able to get through my day without having some sort of flashback. Her daughter, Autumn, began sobbing and screaming in the middle of her 7th grade Social Studies class. It took three weeks before she felt strong enough to return to school. When Mr. Orange, a former minor league baseball player, recounted the night Greg had been shot, it was as if he was reliving it. The muscles in his face tightened. His eyes become wide with fright — and anger. “That sight is still there. I see it every day and every night,” he told us. “And I do this.” He had begun to cry. “I feel so inadequate because there was nothing I could do to protect my grandchild.”

Such anguish can feel like a kind of purgatory. I know a woman — an immigrant from Sudan (who speaks six languages and worked as an interpreter) — whose son had witnessed a murder and was executed to silence him. I met Afaf Ahmed a year after Khalid was killed, and she had trouble leaving her house. Often, I’d come by and pots and pans would be piled high in the sink. She’d be curled up on her couch in a nightgown, even late in the afternoon. At one point, she told me that for weeks she had had a bitter, almost metallic, taste in her mouth. She couldn’t rid herself of it, and it only intensified when she ate, so she had stopped eating. She told me that the only thing that helped was sucking on candy, but even that only diminished the bitterness and didn’t erase it.

One day when she had taken her younger son, who was four, to Lake Michigan, she reached into her pockets and realized she’d forgotten to bring any candy. The metallic taste was unusually strong, so she scooped up a small handful of sand and slowly sucked on it. It took away the bitterness. The sand gave her taste. It is, I suppose, the equivalent of finding solace in an empty room. She purchased bags of playground sand from Home Depot and told her husband it was for their son, but when he discovered that she had been eating it, he began cooking elaborate Sudanese meals, mostly lamb, which Afaf ordinarily savored. But nothing kept that bitterness away like the sand. She had to stop a few months later when her doctor informed her of an alarming iron deficiency.

“I’m alone now,” she told me. “Nobody wants to be with me. It’s like lenses. I see everything through this tragedy.”

The violence of our cities saps the spirit of even the most spirited people. People like Afaf and Gregory Robinson’s family pull inwards. They stop talking. They experience flashbacks. They wilt under the dark skies. Sometimes they become unusually anxious or agitated. A principal at an elementary school once told me that he could always tell when it was the end of the day because the school would begin to shake with activity. Students would get into altercations. They’d run down the hall, slam lockers and holler at each other and teachers. They were, in essence, preparing themselves for the dangerous walk home.

In recent years, there’s been a robust and urgent conversation about how we can best assist soldiers returning from the battlefield in Iraq and Afghanistan. Many, as we now know, suffer from post-traumatic stress disorder. Yet we’ve neglected those here. Consider that in Chicago alone over the past 20 years, more than 15,000 people have been murdered. (Chicago isn’t even in the top 10 most violent U.S. cities.) Each has left behind family and friends. Moreover, many of those murders occurred in public places, on the street or in a park or alleyway, and so have been witnessed by others.

Walk into a classroom in any inner-city school and ask how many have lost a loved one to violence or have witnessed a shooting. Virtually every hand will go up. (In a national study, [PDF] the CDC found that 42 percent of all teenagers have witnessed violence in their community.) And most will tell you they’ve never talked about it. In fact, children are often discouraged from sharing their experiences out of fear that if they do they’ll somehow be held culpable for the crime they’ve witnessed. I’ve encountered children who’ve had flashbacks, others who suffered from depression and some who had physical ailments resulting from the stress. A study out of Johns Hopkins School of Public Health has found, not surprisingly, that children exposed to violence tend to do less well at school.

Over the course of one six-week period, Myra Sampson, the principal at the Community Christian Alternative Academy on Chicago’s West Side, lost two of her students to shootings. Students would stop her in the hall, and tell her, “I’m going to be next.” She told me that the kids were in such a heightened state they couldn’t concentrate. One boy had to be hospitalized because he was having auditory hallucinations that one of the deceased students was talking to him. “What’s going to be the impact of having a group of young adults who shut off?” she asked me.

Steven Marans, a psychoanalyst at the Yale Child Study Center, has asked himself this question a lot. Marans heads a pioneering program in New Haven where the police, who are trained in trauma impact, often refer a child involved in violence, whether as a victim or witness, to Yale for counseling. Marans told me two things have surprised him. One is that those children who are offered a way to process what has taken place are in the future more likely to trust people — and to cooperate with the police.

But perhaps more intriguing is this: When young children are referred to the center after being exposed to an act of brutality, they’re asked to draw something, and what they draw is typically an idyllic scene — a home behind a picket fence, sunshine, birds. Just the opposite of what you might expect. It is, Marans posits, an effort to regain some control over what they’ve seen, to stop feeling helpless in the face of danger. Without any intervention, these children, as they get older, find ways to establish control, and often that can mean distancing themselves from those around them. A 12-year-old boy once told me, “I don’t have friends, just ‘associates’. Friends you trust.” It can also mean that they take an attitude of “don’t mess with me.”

“Becoming aggressive is one way of adapting, of trying to gain some control over your environment,” Marans says. “Don’t be scared. Be scary.”

Psychologists report that children exposed to street violence show the same kind of post-traumatic stress disorder we see in veterans who’ve returned from combat. Yet there is nothing post about the trauma. They still have to navigate the perilous landscape of their neighborhood. At war, there’s a sense of common purpose, that someday there’ll be a resolution to the conflict. Not so in our inner cities. The violence is ongoing, and often seemingly random. (Last month, the CDC released a study that indicated that contrary to popular thought, most street violence is not related to the drug trade but rather is a result of other conflicts, often over seemingly small matters.) There’s no place of refuge or safety.

“One of the things that gets destroyed from ongoing trauma is the capacity to know whether or not there’s safety or danger around you,” Brad Stolbach, the director of the Child Trauma Center at Chicago’s LaRabida Children’s Hospital. “You can’t read people, and often you see everyone as hostile.”

These are communities that are back on their heels, or to borrow from the language of psychologists, are hyper-vigilant. Consider the Block Club signs, some of which appear in the film. Ordinarily markers of neighborhood pride, these signs more often today speak to people’s fears. No Gambling. No Drug Selling. No Drinking Alcohol. No Loitering. No Loud Music. Even the police, who are armed and trained, feel threatened. When late last year a Chicago police officer was shot, the police department offered a reward for any information leading to the arrest of the shooter. When they walked the streets of the neighborhood, handing out leaflets announcing the reward, many wore body armor and carried assault rifles.

Clearly, we need to make these communities safe — both physically and emotionally, places where people feel secure in being themselves. But along with that, Marans and others urge, we need to give both adults and children the tools to grapple with what they’ve seen and heard. Many of the answers are out there (and in fact we see some of it in the film): mentoring, after-school programs, counseling. “What’s tragic is that we know the answers, and we know how to muster the kind of intervention strategies that will be helpful,” Marans told me. “But we seem unwilling.”

In the wake of the murder of her two students, Myra Sampson did something rather simple: She set aside 20 minutes each morning for students to meet in small groups with a teacher. The students were encouraged to talk about what’s going on in their neighborhoods, what’s going on in their lives. If necessary, students were referred to a counselor, but more than anything these morning sessions made the students feel less alone.

Eddie Bocanegra, one of the “violence interrupters” in the film, has undertaken a pilot project. Eddie has two brothers who served in Iraq, and one returned deeply troubled by what he’d seen and what he’d done. As he shared his difficulties in adjusting to civilian life, Eddie saw parallels to what he had experienced in the streets. So Eddie has contacted veterans groups, and beginning in April, plans to have former soldiers who’ve battled PTSD come speak to gang members, not necessarily to pull them off the streets, but rather to prod them to consider how the violence has torn away at who they are. These kids often appear without affect, without feelings, without remorse — all clearly the effects of experiencing trauma. “They can have whole entire aspects of their selves that are never felt,” Stolbach says.

A number of years ago, a young man I knew was getting out of a cab on the West Side when two men yanked him aside and jumped in the backseat. One of the men put a gun to the head of the cab driver and demanded his money. The cabbie panicked and pressed down on the accelerator. As he did, the man fired his gun, killing the driver. My friend watched all this, paralyzed with fear and shock. I learned about the incident the next morning, and I immediately called my friend, but I couldn’t reach him. I tried all day (this was before cell phones) but as it turns out, he was out shopping for clothes.

I was both dismayed and angry. Shopping? He’d just seen someone killed. The facile explanation is to say he didn’t care or that he’d had become hardened to the violence. (He’d seen other people shot, as well.) But as it turns out, his behavior wasn’t all that unusual. To protect himself, he had lost the capacity to feel fear or anger or grief. He had cut himself off not only from others, but also from himself. The children who grow up amidst such violence become kind of spiritual nomads with no one to turn to, often not even themselves. I remember how Gregory Robinson’s sister, Autumn, made a point of telling us she now keeps to herself. “I just want to be left alone.” What could be a more acute form of despair than loneliness?