OAKLAND -- Luis Romero is concerned about his cousins, two small boys whose father, 39-year-old Jose Esparza, was shot dead Sunday while returning home from St. Louis Bertrand Church in East Oakland.

"They're going to be traumatized," said Romero who, at 16, is already familiar with the effect that the violence of Oakland's streets can have on young children. "One of them might want to get payback, and it's never going to stop." Esparza's death hurt his children, Romero said, and "hurt people, hurt other people."

In his own way, Romero has captured a sentiment that scientists, psychologists and experts on trauma across the country are beginning to understand with greater clarity.

"Witnessing a traumatic event is a mental injury," said Miriam Birkman, an assistant clinical professor at the Yale School of Medicine's Child Study Center.

In response, the body's usual coping techniques, the so-called fight or flight response, can become paralyzed, altered or damaged, a state of emotional paralysis psychologists refer to as disregulation.

"The idea is that the brain has a certain way of working and that in traumatic moments memories get laid down in a different way, so thinking, feeling and behavior get disregulated," she said.

Like physical injuries, the recovery process can be hazy, uncomfortable and may take years. For children, especially, the loss of a parent to violence amounts to "the shattering of a worldview," Birkman said.

Within the last month in Oakland, children seem to be getting swept into the violence with more regularity, causing health officials and experts to take note. On Aug. 8, 3-year old Carlos Nava was hit by stray gunfire in a shootout. He died instantly. Two weeks later, a 6-year-old and an 8-year-old were both hit by bullet fragments in another shootout. And on Aug. 28, Esparza's 6-year-old boy watched as his father was gunned down in cold blood after thieves tried to rob him outside the El Pueblo bakery near their home.

"When you perceive danger your body gears up, so this happens in little kids," said Chandra Ghosh Ippen, the associate research director of the Child Trauma Research Program at UC San Francisco. "When something bad happens, they calm down by checking out their parents."

As children monitor their parents' behavior, they learn how to interpret the world -- its joys as well as its threats.

But when parents are unable to prevent violence or, worse, when they are involved in it themselves, children are thrown off course, and may not know where to turn for support.

Evolution

Scientists are learning more about the effects of trauma on children by studying the way children's brains record memories. When children experience traumatic events, their brains are wired to record the experience in a way that will help them survive future threats to their safety. In particularly stressful moments, such as a shooting, a child's brain will begin to wire everything about the event into the same neural pathways.

"You don't just have a shooting, you have gunmen coming, people sensing danger, pushing, the aftermath, and it all gets embedded at a neurological level," Ghosh Ippen said.

Children need to know what is dangerous. However, a traumatic experience can have the effect of rewiring the brain in such a way that little things -- the sound of a car, a look of fear on someone's face, the smell of french fries -- can become trauma reminders, or what psychologists call "triggers." Long after the trauma is over, the world can remain a fundamentally threatening and scary place because it is now filled with triggers that remind the person of the initial trauma.

"We want to think that kids don't remember, but little kids do," Ghosh Ippen said.

Childhood grief

Jose Esparza took his youngest son to a Chuck E. Cheese's for a recent birthday. On most other weekends, he took his sons to Lake Merritt, or on bicycle trips or to the beach. Because of the violence surrounding his death, scientists say that, hypothetically, any one of those peaceful memories at the beach or the lake could become a trigger for his sons in years to come.

"Think about the word 'Dad' being a trigger," Ghosh Ippen said. "That's the phenomenon of childhood traumatic grief."

The challenges for children are unique. Some kids are more resilient than others. Others are more comfortable seeking support from loved ones. And children react differently to traumatic events based on several factors, including age, family structure and support, and their own personalities.

Six-year-olds, for instance, are just beginning to understand their own sense of identity and independence. The loss of a parent to violence can halt that progress in its tracks. Slightly older children, those on the verge of adolescence, are developing a sense of fair play, of right and wrong. But they're also at a stage where they want to fit in. Trauma can disrupt that by interfering with their cognitive development.

"That's where it gets problematic," said Hilary Hahn, a clinician at Yale's Child Study Center, "Because how do you run away from your own thoughts and fears? The fear is about being killed, about your own body or someone you love, it's a really scary process when your brain is out of control."

Environment matters

In some neighborhoods, where many children have experienced violence, the stakes for parents raising small children are even higher.

"Safety is a real issue for a lot of mothers in some neighborhoods," Ghosh Ippen said. "If you step out of line, you'll be dead, so a lot of these kids grow up not sure whether they'll have a future."

When a neighborhood is filled with traumatized people, all of whom have multiple triggers, the neighborhood itself becomes unsafe. Psychologists can measure this by looking at people's "affect," the attitude or demeanor they present to the outside world. In other words, the more calm and reasonable people feel on the inside, the more their neighborhoods and their circles of friends and family will reflect that state of mind.

"One thing we know is that when people's affect is calm, they're better able to have perspective," Ghosh Ippen said. "When their affect is charged, when they're triggered, they're more likely to act out, and to stereotype." And that's exactly the kind of behavior that keeps children, and the adults they become, in endlessly repeating cycles of violence.

It's also why Luis Romero is keeping a close and watchful eye on his cousins. The little one, he said, is paranoid and scared. The older boy's fists are purple with bruises from hitting the wall in rage. "He wants to kill whoever killed his father," Romero said. "It hurts to hear my cousin say he wants to kill them. It makes me want to kill them, too."

Contact Scott Johnson at 510-208-6429. Follow him at Twitter.com/scott_c_johnson and Twitter.com/oaklandeffect.

shooting victim remembered
A rosary for Jose Esparza will be held
6 p.m. Tuesday at Santos Robinson Mortuary in San Leandro and funeral services are 10 a.m. Wednesday at St. Louis Bertrand Parish in Oakland. A bank account in Jose Esparza's name has been set up for anyone who wants to help the Esparza family: Wells Fargo Bank, account #1329796690.