The lights went out, and we were left in the darkness.
Literal
Light [subject-が] extinguish, we [topic-は] darkness [in-に] were-left.
Tight phrasing: 消える (plain form, not te-form) joined by comma, 暗闇 ('darkness') without の中, and 残される (plain passive of 残す). 残す is gentler than the compound 取り残す ('leave behind, abandon'); both passives can describe the same scene but with subtly different shades of being left behind.