Two days of torrential downpours in Mamasa district triggered a landslide that went into a river, causing the waterway to burst its banks, said Roki Asikin, head of the rescue agency coordinating the search.
Eleven adults in the village were killed in Thursday’s flood and seven people were missing – including four children and a six-month-old baby, he said.
Indonesia has been repeatedly afflicted by deadly floods and landslides in recent years during its wet season, which lasts around half the year.
Environmentalists blame logging and a failure to reforest denuded land in the world’s fourth-most populous country for the frequent flooding.
Floods in Indonesia’s Papua region killed more than 140 people and displaced around 5,000 in 2010.