Family and friends say the teen also had autism.
The principal at Eagle Rock Junior/Senior High School notified students Wednesday.
"It is with great sadness that we inform you that we were notified of the death of one of our students," Principal Mylene Keipp said in a message to the school community.
The school is offering crisis counseling for students.
The incident happened around 2:30 p.m. Tuesday in the area of Broadway and Colorado Boulevard.
When the teen jumped, he landed on a man with two young children. The man was transported to a hospital with non-life threatening injuries. The children were not hurt.
If you or someone you know is in emotional distress or considering suicide, call the National Suicide Prevention Lifeline at 1-800-273-TALK (8255).