The North County Times says investigators determined that 19-year-old Lance Cpl. Mario Arias Jr. was attacked at the San Diego County base over the weekend.
Ed Buice of the Naval Criminal Investigative Service says the suspect then jumped from a third-floor balcony and received significant injuries. He's expected to recover.
His name isn't being released until charges are filed.
Arias was from Canoga Park and enlisted last year. He was an air crew trainee from Marine Light Attack Helicopter Training Squadron 303 of the 3rd Marine Aircraft Wing.