A 17-year-old U.S. high school student who fell from the Capilano Suspension Bridge and died earlier this year was under the influence of LSD, according to a coroner's report obtained by a California newspaper.

Daniel Cho was on a graduation trip with 103 other students from San Mateo, a large suburb south of San Francisco, when he died.

Authorities say he fell after climbing a 1.2-metre-high railing at a viewing platform, unbeknownst to the seven teachers and 17 volunteer chaperones who were accompanying the students.

A coroner's report into his death indicates Cho took LSD with two friends while on a bus from Seattle, Wash., to Vancouver that day, according to the San Mateo Times.

The report ruled Cho's death an accident.

Police say the platform Cho climbed is hidden by trees and steep terrain, and that he had been told to stop climbing over safety barriers at least once before his fatal fall.