They're frustrated, angry, isolated. Their hormones are raging, and their rage is mounting. They want revenge, attention and - although they're only in their teens - they have a gun guaranteed to get it for them.

"The gun gives them a sense of power," said Karil Klingbeil, director of social work administration for Harborview Medical Center. "They've finally got something on their side. They're going to have the last say; they're going to show everybody."After the shooting Thursday in Springfield, Ore., local experts in adolescent behavior pieced together a disturbing psychological profile of the troubled teens transformed into schoolyard assassins across America.

The portrait is one of isolation and alienation.

"Twenty years ago, we had people firing from towers into the crowds below," said Bill Womack, a child psychiatrist at Children's Hospital in Seattle. "The profile that emerged from those multiple killings was of someone trying to draw attention to themselves, someone saying to the world, `Acknowledge me; pay attention to me.' "

For the teen assassins, it's a lonely cry and a bloodcurdling one. Since fall, armed adolescents have shot almost 40 students and teachers on high school grounds. Thursday's rampage in Springfield raised that number to more than 60.

Psychiatrists call it a "contagious epidemic," one feeding on itself.

"For the most part, these are very depressed kids with a lot of pent-up rage and no other outlet," said Stephen Cummings, a licensed clinical psychologist who works with children and adolescents in Seattle.

"When these stories hit the news, the kids have these fantasies - and some take it a step further and act it out in reality."

Many of the teen killers show signs of clinical depression: loss of appetite and energy, difficulty in school and lack of friends. They may have thoughts of killing themselves.

Most have very poor coping skills. They tend to be on the fringe of their peer groups, out of the "in" group, loners or wannabes. Many come from dysfunctional families.

And most have a record of trouble. Statistics on school deaths from the National School Safety Center in Westlake Village, Calif., found 40 percent of the young killers had a past criminal record, 35 percent were involved in gangs, 24 percent were under the influence of alcohol and drugs - and fully 70 percent had previously brought a weapon to school.

Brandishing guns or bragging about them can bring a social misfit immediate attention. "Anyone who verbalizes threats like this needs to be taken very seriously," Cummings said. "These kids need some help. They've probably been crying for it for a long time."

Although a single incident may push such teens over the edge - a bad grade, a girlfriend's rejection, an argument with Dad, or, as in the case of 15-year-old Kipland Kinkel in Springfield, expulsion from school - mental health experts say the anger that finally erupts probably has been brewing since childhood.

And fantasies of retaliation may have simmered along with it.

"Most likely, this is a kid with internal anger, a feeling that nobody cares for him, that he is not really a part of humanity," Womack said. "He may feel he has suffered so much in his lifetime that he wants someone to feel the same pain he feels."

Other factors intensify the feeling of isolation for teens. One is adolescence itself.

It's a time of rapid hormonal changes, mood swings, flagging self-esteem, acne, budding bodies and foreign feelings. It's a time when children impulsively try to learn how to become adults, when they test the waters of right and wrong, when they ponder the question "Who am I?"

"It's a very vulnerable time, extremely vulnerable," Klingbeil said. "Hopelessness, despair, frustration, depression, identity confusion - all that stuff can begin to play a role here."

Boys can be particularly vulnerable to explosions of rage.

"Girls have always had the advantage in our culture of being allowed to express themselves, not being stoic," Womack said. "If they get mad, they'll stand there and mouth off at you, argue, explain what they're angry about.

"Boys can't do that. If they do, they're not being masculine, not behaving as a boy should. So they tend to hold it in.

"Then, when they really get angry, that's when they may act out, take aggression at someone outside themselves."