WASHINGTON (CNN) -- Eleven-year-old Carl Joseph Walker-Hoover liked football, basketball and playing video games with his little brother.
Rep. Carolyn McCarthy says the effects of bullying are becoming more severe.
But on April 6, after enduring what his mother called "relentless" bullying at school, Carl hanged himself with an extension cord in the family's Springfield, Massachusetts, home.
"What could make a child his age despair so much that he would take his own life? That question haunts me to this day, and I will probably never know the answer," Sirdeaner Walker said in a House Education and Labor Committee hearing on school bullying.
"He had just started secondary school in September, and we had high hopes," she said. "But I knew something was wrong, almost from the start." Watch Sirdeaner Walker describe finding her son's body »
He didn't want to say at first, she said, but reluctantly told her of classmates who called him names, "saying he acted gay and calling him faggot," Walker said.
"Hearing that, my heart just broke," she said.
Rep. Carolyn McCarthy, D-New York, said the emotional and physical effects of bullying are becoming more severe and that the acts of bullying can continue outside school.
According to the National Youth Violence Prevention Resource Center, about 30 percent of school-aged children in the United States are estimated to be involved in bullying, as either a bully or the target of a bully.
Steve Riach, the founder of Heart of a Champion Foundation -- a nonprofit organization that says it offers educators an "innovative and effective approach to developing character in the lives of their students" -- said his organization has learned that students recognize that school safety cannot be accomplished only with security guards and metal detectors.
And students "have told us that emotional safety is every bit a concern as physical safety," he said.
Walker called school bullying a national crisis.
"I've learned that bullying is not an inevitable part of growing up. It can be prevented, and there isn't a moment to lose," she said.
"We need a national solution to deal with it," she said.
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