A student was ordered to leave UC Riverside after police said they searched an apartment on campus and found an assault rifle, five high-capacity magazines and a journal with hand-drawn images of a violent act.
The content of the drawings was not provided.
Police are presenting the case to the Riverside County district attorney to decide whether criminal charges will be filed.
In the meantime, the student is on provisional suspension and cannot return to campus pending the outcome of an administrative hearing.
Police discovered the gun and ammunition Friday while executing a search warrant at the Northern District residential apartments after evidence of a weapon emerged on campus.
Police said in a statement that the incident was not related to other campus events. The same day, the UC Riverside administration reached an agreement with pro-Palestinian protesters to close an encampment that was set up on campus on April 29.