JAKARTA, Indonesia (AP) — The death toll from a flash flood in Indonesia’s South Sulawesi province rose to 21 on Wednesday with two people still missing, an official said.

National Disaster Mitigation Agency spokesman Raditya Jati said search and rescue operations were hampered by thick mud covering roads and houses, and rain was continuing to fall.

Ten other people were injured in the flooding, which affected six subdistricts in the province, he said. As of Wednesday evening, 2,650 people had been evacuated.

North Luwu district official Indah Putri Indriani said the flooding began Monday evening and was triggered by heavy rains that caused three rivers to overflow.

Heavy rains cause frequent landslides and flash floods in Indonesia, where millions of people live in mountainous areas or near flood plains.