By the time the floodwaters swallowed the ground floor of Muda Sedia hospital in Karang Baru, the building had become an island in a torrent of brown water and the power was failing. When the electricity finally cut out, a baby on oxygen support upstairs died.

As a rare cyclone-driven storm tore across northern Sumatra late last month, hospital director Andika Putra had moved patients to the second floor in this town at the edge of Indonesia¡¯s northernmost province. Fast-moving currents isolated the compound, trapping patients, staff and neighbors for days. Nine others perished.

¡°This scale of flooding has never happened before in the hospital¡¯s history,¡± he said, standing outside the building in a light rain. Behind him, the waters had left broken medical equipment and a thick layer of mud spread across the waiting room floor.