What this should read as: 関係者以外立ち入り禁止: Authorized personnel only.
This time on our mistranslations, we have a sign that someone found in a mall in Japan that has a very bizarre collection of phrases. Whoever tried to translate this jargon was either translating the definition of each Japanese word, or used a machine translation. It seems as though she/he did not comprehend the structure of the phrase in English. When translating signs, remember: keep it short and simple. Otherwise you might make a mess of a translation.