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.