Flash floods caused by torrential rain have led to the deaths of 41 people in Indonesia, its BNPB disaster management agency has said.
At least 49 families were affected on the island of Flores, BNPB spokesman Raditya Jati said, adding: "Dozens of houses were buried in mud in Lamanele village."
On Adonara island to the east of Flores, a bridge collapsed and rescuers were battling heavy rain, strong wind and waves, Mr Jati said.
Dozens of bodies have been recovered.
At least three others have died in a landslide in neighbouring East Timor, including a two-year-old child.
A boarding home for students in the capital, Dili, was pictured being washed away.
East Timor's deputy prime minister, Jose Reis, said it was the worst incident to affect his country in 40 years.
Power supplies were cut and the presidential palace was flooded.
"Heavy rains and overflowing water have drowned people's homes and have also claimed the lives of several victims," Mr Reis said.
"There are roads that have collapsed. Trees have fallen and made it difficult to access some areas."
It is feared more severe conditions could be on the way.
Indonesia's weather agency said a tropical cyclone was approaching the Savu Straits between the southern part of Nusa Tenggara province and East Timor's north coast.
Seasonal downpours cause frequent landslides and floods in Indonesia, killing dozens of people each year.