9-year-old Jamel Myles committed suicide just four days into the school year after being bullied by his fourth-grade classmates for being gay, his mother says.

Myles’ mother, Leia Pierce, found him dead in their Colorado home. Denver authorities determined the cause of death was suicide.

“He looked so scared when he told me. He was like, ‘Mom I’m gay,’” Pierce tells KDVR-TV. “And I thought he was playing, so I looked back because I was driving, and he was all curled up, so scared. And I said, ‘I still love you.’”

Pierce says, “The same kids who picked on him last year were even meaner to him once he came out and said he was gay. They hurt my baby.”

While suicide rates for children are still lower than those for teenagers and adults, child suicide-related deaths have been on the rise. Experts state that suicidal behavior in children under 13 is different than for older people.

John Ackerman, a suicide prevention coordinator for the Center for Suicide Prevention and Research at Nationwide Children’s Hospital and psychologist, tells CNN, “Impulsivity plays a big role in the suicidal behavior of young kids not thinking through actions.”

As children have yet to learn how to carefully process and engage stressful emotional responses and cues, they are more impulsive and therefore prone to suicidal behavior.

According to the US Centers for Disease Control and Prevention, the percentage of children hospitalized for suicidal attempts and thoughts have doubled between 2008-2015. Research indicates that they occur highest in spring and fall—the times school is open.

Lisa Boesky, a clinical psychologist who studies suicidal behavior in adolescents, tells CNN, “Many people, including medical professionals, think suicide is a teenage problem. But suicide can happen at very young ages.”

Boesky also states that a common misconception people have when attempting to identify suicidal behavior in young children is that “many people look for signs of depression.” However, this is more commonly found in adolescents, who show more mood swings.

A 2016 study concluded that young children under 13 with mental health issues are more prone to “impulsively responding to problems in their lives.” Ackerman shares that because young children tend to be more impulsive in suicidal behavior, it is important to diagnose and highlight impulsivity as a factor. He adds that young children also “don’t understand the permanence of death in the same way.”