I contacted the station staff, but the man left the scene and went out through the ticket gate.
Literal
Station-staff [to-に] contacted [but-が], man [topic-は] that place [object-を] leave, ticket-gate [object-を] exit went.
駅員 'station staff.' 立ち去る 'to leave the scene' — 立つ 'to stand' + 去る 'to leave.' 改札口 'ticket gate' — a distinctive feature of Japanese train stations. 出て行った 'went out' — 出る + ていく for movement away. The sentence reads like an incident report or witness statement.