BERKELEY (AP) — The University of California, Berkeley says 500 incoming students have not taken a mandatory class on sexual violence.

UC Berkeley Spokeswoman Claire Holmes said Thursday that officials were notifying the students via email that they had not fulfilled the requirement and will be blocked from registering for spring classes if they do not meet an Oct. 1 deadline.

Holmes said officials do not know why the students had not gone through the class that can be taken online or in-person.

The school is under federal investigation for its handling of sexual assault complaints, and a state audit in June found that the administration did not ensure attendance at sexual assault education workshops for freshmen. Only 52 percent of the incoming class attended the programs in 2013, school data shows.