The student at Tahquitz High School is being treated for the contagious disease and is expected to recover, officials said. The student will not be allowed to return to school until receiving medical clearance.
In the meantime, officials are working to identify and examine any students or staff who may have been exposed. Officials have sent letters to the families of about 300 students who may have been exposed.
The county is offering a free TB screening later this month at the school.
"While the risk of infection is slight, it is important that those who are notified take the time to get tested," Riverside County Public Health Officer Dr. Cameron Kaiser said. "The testing is simple, doesn't take much time, and can provide peace of mind."
Tuberculosis is an infectious disease that can cause serious problems in the lungs, including chronic cough, bleeding and chest pain, and can be fatal if untreated. It is spread through the air when people infected with active TB cough, spit, speak or sneeze.
The Hemet Unified School District has scheduled a meeting at 6 p.m. Thursday at Tahquitz High School for parents who have questions and concerns.
More information is available at the school's website here.