KOTA BATU, Indonesia (AP) — Flash floods from torrential rains on Indonesia’s main island of Java killed at least six people and three others were missing, officials said Friday.

The National Disaster Mitigation Agency said rivers on the slopes of Mount Arjuno overflowed their banks on Thursday and their muddy waters inundated five hamlets in Kota Batu, a city in East Java province. It said 15 people were swept away and six were later rescued.

The agency chief, Ganip Warsito, said heavy rains are expected to continue and increase until February, partly because of a La Nina weather pattern.

Rescuers retrieved a body near Brantas river basin late Thursday and five more bodies were found on Friday, said the agency’s acting spokesperson Abdul Muhari in a statement. They are still searching for the three missing people, he said.

Relief efforts were hampered by blocked roads covered with thick mud and debris.

Photos and videos released by the agency showed a damaged bridge, and houses and cars covered in thick mud.

Authorities were beginning to evacuate people in affected areas to government shelters, Muhari said.

Severe flooding was also reported in other areas of the country but no casualties were reported, the agency said.

Seasonal rains frequently cause flooding and landslides in Indonesia, an archipelago of 17,000 islands where millions of people live in mountainous areas or near fertile flood plains.

The latest major floods were in April, when Tropical Cyclone Seroja triggered landslides and flooding that killed at least 183 people on Indonesia's side of the Island of Timor, which the country shares with East Timor. Another 42 people were found dead on East Timor's side of the island. The cyclone damaged thousands of homes and thousands of people were displaced.