Four high school wrestlers in Oklahoma have been charged with sexually assaulting two other wrestlers on a bus.

Officials with Norman North High School have said an incident involving students from the school occurred as students were returning from a tournament on a bus on Jan. 9. The victims are 16 and 12 years old.

Online court records show an 18-year-old, a 17-year-old and a 16-year-old were each charged Monday with three counts of rape by instrumentation. Another 17-year-old was charged with one count. Court records do not list attorneys for any of the teenagers.

School officials have said an undisclosed number of students, a coach and an adjunct coach have been suspended.