(CNN)A missing nonverbal California teenager was discovered after a rescuer heard him clinking rocks.
The teen, who is developmentally disabled, was spending the day at Crescenta Valley Park in Glendale with his mother and sister when he went missing at about 10 a.m. on April 3, according to the Los Angeles County Sheriff's Department. The park, just south of Angeles National Forest, includes some heavily forested areas.
John Gilbert, coordinator for the Montrose Search and Rescue Department, told CNN that the 16-year-old was last seen walking straight up a hillside in what the family called an "uncharacteristic" move. His mother and sister were unable to follow him. He was missing for about seven hours.
While briefing the search party about the missing boy, his mom mentioned that he enjoyed playing with rocks, Gilbert said.
During the search operation, a member of the LASD's Montrose Search and Rescue team heard the sound of clinking rocks and remembered the teenager's interest.
The search member followed the sound and directed a helicopter to look down the canyon toward the sound. There, they found the teen sitting under a tree. According to the department, the search member "worked to build a rapport with the teenager" and then led him up the mountain, where he was treated by paramedics and reunited with his family.
Gilbert noted that the teenager was in "really good shape" with no notable injuries.
"Our Department was thrilled this incident had a happy ending," wrote the department on Facebook.