High school student dies after homemade rocket experiment goes wrong

This Monday, April, 4, 2016 photo provided by Safety For Citizens shows sheriffs officials on the scene after a homemade model rocket exploded at Madrona Elementary School in Thousand Oaks, Calif. (Joel Council/Safety For Citizens via AP)

Authorities in Southern California Tuesday were trying to determine what caused a homemade rocket attached to a skateboard to explode, killing a high school student and injuring his friend.

Bernard Moon, 18, of Thousand Oaks, died after the blast on Monday night. A 17-year-old suffered minor injuries and was hospitalized in stable condition as of Tuesday.

The two teens were honor students at Thousand Oaks High School. The blast occurred in a courtyard at Madrona Elementary School in Thousand Oaks. They were experimenting with a skateboard attached to a homemade rocket as an engine, authorities said.

The rocket was about a foot long and three-quarters of an inch in diameter, Ventura County sheriff's Capt. Garo Kuredjian said.

"It wasn't meant to go up into the sky," he said of the rocket. "It was meant to go horizontally to propel a skateboard."

Ventura County fire officials said Moon was handling a propane cylinder at the time of the accident, according to the Los Angeles Times.

Details of the chemicals used and the rocket’s design were not immediately released and it’s unclear whether anyone was trying to ride the skateboard at the time of the blast.

Boy Scouts and Girl Scouts were meeting at Madrona Elementary when the school suddenly shook.

"Nobody could really discern what it really was because it was a huge explosion. It was just all at once. Just a 'boom!' " Tammy Coburn, who was attending the meeting, told reporters.

A nurse who was attending the meeting tried to help Moon, but he died at a hospital.

Thousand Oaks High School expressed their condolences on Twitter.

Moon was a varsity tennis player at the school, an honors student and had been accepted into the University of California, Berkeley and Brown University, friends said.

Moon had placed in the Ventura County science fair in 2015 and 2014. This year's fair was scheduled for April 20.

The experiment at the elementary campus wasn't sanctioned by any school, and the victims likely were using the courtyard because it's an open space, Kuredjian said. Classes at the elementary school northwest of Los Angeles were canceled Tuesday.

The Associated Press contributed to this report.