KANSAS CITY, Mo. — A celebrity’s son plunged eight stories to his death Feb. 26 in Los Angeles after writing a note that said he was unhappy.

Two Pennsylvania girls in their midteens stood in front of an onrushing Amtrak train late last month, having texted how upset they were by a boyfriend’s death in a traffic accident.

An academically and athletically gifted junior at Odessa High School came home drunk six years ago, climbed the stairs to his bedroom and put a rifle to his head.

“As a parent, I didn’t notice the difference between depression and normal 15- and 16-year-old behavior until after the fact,” Tracy Peter said of her son, Evan Hedicke, who was 16 when he killed himself.

Warning signs include self-harm, inability to concentrate, personality changes and changes in eating habits.

What experts are noticing is that after a decline in the 1990s, the number of young people who kill themselves began to rise about five years ago.

Although no one can explain with certainty the reason for the increase, experts point to teenagers having more pressures at home and at school, financial worries for families and an increase of alcohol and drug use.

“This is a very dangerous time for our young people,” said Kathy Harms, a staff psychologist at Kansas City’s Crittenton Children’s Center, which provides psychiatric care for children and adolescents. “We’re seeing more anxiety and depression in children of all ages. … We see kids as young as 3 who come in.”

In this country, a teenager takes his, or her, own life every 100 minutes, according to Suicide.org, a national suicide-prevention Web site.

“Teens think they are invincible, so when they feel psychological pain, they are more apt to feel overwhelmed by hopelessness and the belief that they have no control over their lives,” said Tony Jurich, the author of a 2008 book on suicidal adolescents.

Hopelessness and helplessness is “the Molotov cocktail that triggers teen suicide,” said Jurich, a professor at Kansas State University.

The issue is in the headlines again after Marie Osmond’s 18-year-old son jumped off his apartment balcony. Michael Blosil, son of the 1970s TV and music star, left a note thanking a friend and detailing a few last moments, according to news reports.

Schools, counselors and psychologists across the nation see more young people battling severe depression and other psychological issues.

A study released in January found that five times as many high school and college students today deal with mental health issues as those surveyed during the Great Depression.

Tracy Peter says she wishes she could have gotten her son treated in time. More than five years after his suicide, she knows the warnings were there.

“What if I had recognized the signs?” she said.