The Public Safety Commission (公安委員会, Kōan'iinkai?, English manga: "Protection Committee" or "Security Enforcement Committee") is a group of enforcers on school grounds charged with protecting the academy. These members use their status to their advantage, similar to hall monitors, and anyone who opposes them is delivered swift punishment through methods of imprisonment and torture. They collect tribute and bribes from clubs, and if they do not pay, they will be shut down.
The Public Safety Committee have a long-standing rivalry with the Newspaper Club for exploiting their true nature, and had decimated the previous Newspaper Club in the past, leaving Gin the only member.
According to Deshi in the anime, she, Kuyo, a bespectacled male who becomes a cerberus, and a tall, sadistic male who becomes a golem are referred to as the "Four Kings".
In the end after Tsukune's identity is revealed (both manga and anime) it is likely the Headmaster removed the corrupt members from the School Police and replaced them with ones that actually did their jobs without becoming corrupt as they do not cause trouble for the Newspaper Club (or anyone else for that matter) afterwards.