Hayward Unified School District released a statement on the incident, saying the three students were involved in an altercation.
Neither of the injuries were life-threatening.
One of the injured students went to the school office and then went to a local hospital. The other student fled campus and was brought to the hospital in a private vehicle.
The district says there is no ongoing threat and they are working with the Hayward Police Department in their investigation.
Additional security officers were on campus Tuesday.
The district did not say if the student with the knife was arrested.