Some parents of students at the University of California, Berkeley, hired private security workers to patrol near the campus, something the school says should be left up to the campus police.

The group, called SafeBears, says it represents more than 1,300 parents of students at the university. It said it decided to hire the security guards after several crimes involving students last year, including a carjacking near a fraternity house and another one near campus.

The university, which has…