By May 4, the continuous ash fall had caused the Riviere Blanche, the river to the north of St. Pierre, to completely dry up. On May 5, the river became flooded, by an unknown source, and a hot mudflow drove towards the harbour. A sugarmill situated on a bank was buried by the mudslide which killed all the workers inside. The harbour experienced a small tsunami from the flood of mud and water that violently entered the sea. This picture shows the block and ash flows that later filled the valley of the Riviere Blanche.