Where does school security come from?

School security guards come from security companies, some are recruited by the school itself and some by property management companies, but they must have safety qualification certificates and local public security organs for the record. First of all, there are two situations. For example, private schools can recruit their own security guards, or they can find a third-party property company to recruit. For public schools, security guards are of course recruited by third parties, because public schools are not allowed to sign supernumerary personnel themselves. If necessary, supernumerary personnel can only be recruited by labor dispatch companies.