(AP) — Classes are resuming Wednesday at Burwell’s public schools after they were canceled so administrators could prepare new security measures.

A menacing letter sent to Burwell’s city hall last week contains what’s being called a “hit list” of more than a dozen names of Burwell school administrators, teachers and students. No arrests have been reported as officials and investigators try to find out who sent it.

On Monday the school board decided to cancel Tuesday’s classes for the district’s 323 students.

Among the security changes being imposed, the school junior-senior high school will become a closed campus. All bags being taken into the school will be checked, and all high school students and staffers must park in the high school parking lot.

An increased police presence also is expected.