reports that Ozzy Osbourne's son 16-year old son, Jack, was injured Wednesday when he and several friends were attempting cannonballs off the Malibu Pier in Southern California.

The young star of MTV's "The Osbournes" suffered an arm injury, and was taken to Malibu St. John's Urgent Care center for treatment. Norton Wisdom, a Los Angeles County lifeguard, tells the AP, "I looked up and there were a bunch of kids doing cannonballs off the Malibu Pier, which is illegal."

Osbourne was on the pier with a film crew at the time. After his injury, area lifeguards stabilized his arm and treated him for mild shock. The film crew did not have a permit to be on the pier and left the area, Wisdom said.