Typhoon Gaemi claimed the lives of at least four people and forced the evacuation of hundreds of thousands in the Philippines, where parts of the capital Manila are flooded, even as the storm moves toward Taiwan.

Packing sustained winds of up to 165 kilometers per hour, the storm shut financial markets, schools and offices, and forced cancellations of flights and ferries in both archipelagos, where it’s expected to cause billions of dollars in damage. Gaemi is forecast to make landfall in Taiwan late Wednesday.

"This is shaping up to be a significant disaster in an economically and politically sensitive area,” said Chuck Watson, a disaster modeler with Enki Research. The storm is expected to strengthen over the next 12 hours to the equivalent of a Category 4 hurricane, according to data from the U.S. Joint Typhoon Warning Center.