Find the Last Refuge civilians who chose to follow Uulikios deeper into The Upper District.
You encountered Olivan in The Upper District who told you about his neighbors who refused to flee with him. Instead, they chose to follow a priest of Eterra named Uulikios to find sanctuary under the gaze of a statue of the goddess.
When you found the statue all you found and destroyed a crowd of people turned into Void Husks. The man praying at the statue has transformed into a Void creature himself. Defeat Uulikios!