A wildfire raged near a camp for refugees and migrants on the Greek island of Lesbos on Saturday, the latest challenge to the health and safety of thousands living in squalor there.

An estimated 9,000 migrants live in the official camp, known as Moria, and in the makeshift settlement that has sprung up around it. The fire came a day after Greek authorities began relocating people from the island, away from conditions described by aid groups as overcrowded, unsanitary and dangerous.

Videos posted to social media by people in Moria showed a large plume of smoke rising in the distance. In one of the clips, children could be heard shrieking as helicopters flew overhead with water to douse the flames.