Multiple earthquakes are rattling Santorini, a volcanic island in Greece, prompting authorities to dispatch rescuers with tents, a sniffer dog and drones, and to shut schools on four islands. Residents have been warned to avoid indoor gatherings,

Greek authorities have warned of an increase in seismic activity around the Aegean tourist island of Santorini, advising people to avoid four ports, empty their pools, refrain from gathering in indoor spaces and shut schools on Monday.

Tremors between Santorini and Amorgos since Friday led to school closures in Santorini, Ios, Amorgos, and Anafi, as authorities monitor the seismic activity.