Security guards and gaming surveillance officers patrol and inspect property against fire, theft, vandalism, terrorism, and illegal activity. They monitor people and buildings in an effort to prevent crime. Guards must remain alert, looking for anything out of the ordinary throughout their shift. In an emergency, guards may call for assistance from police, fire, or ambulance services. Some security guards may be armed. Unarmed guards generally need to have a high school diploma. For armed guards, employers usually prefer people who have some coursework in criminal justice. Some employers prefer to hire security guards with some higher education, such as a police science or criminal justice degree. Programs and courses that focus specifically on security guards also are available at some postsecondary schools.