PADANG, Indonesia (AP) — The death toll from flash floods and landslides on Indonesia’s Sumatra island rose to 164 on Friday with 79 people missing, authorities said, as rescue workers found their efforts hampered by damaged bridges and roads and a lack of heavy equipment.

Monsoon rains caused rivers to burst their banks in North Sumatra province Tuesday. The deluge tore through mountainside villages, swept away people and submerged more than 3,200 houses and buildings, the National Disaster Management Agency said. About 3,000 displaced families fled to government shelters.

The death toll in North Sumatra province rose to 116, while 25 people died in Aceh. Rescuers also retrieved 23 bodies in West Sumatra, National Disaster Mitigation Agency’s Chief Suharyanto said.

“Mudslides that covered much of the area, power blackouts and lack of telecommunications were hampering the search efforts,” Suharyanto, who goes by a single name like many Indonesians, told a virtual news conference. He spoke from an airport in North Tapanuli district, shortly after conducting an aerial inspection above the devastated areas to see the scale of the disaster.

At a National Teachers' Day commemoration speech, President Prabowo Subianto noted that three aircraft —including a Hercules C-130 and a newly Airbus A-400 — carrying rescue personnel, food, medicines, blankets, field tents and generators were deployed Friday morning as part of ongoing relief operations. 

“We continue to send aid and support the needs of those affected,” Prabowo said. “Many roads are cut off and the weather remains unfavorable. Even our helicopters and planes sometimes struggle to land,” he added.

Prabowo said the disaster highlights growing global challenges such as climate change, global warming and environmental degradation. He suggested that environmental awareness should be strengthened in school curricula.

“We must teach the importance of protecting our environment and our forests, and seriously prevent illegal logging and destruction,” he said.

Footage on the aerial view above devastated areas in the three provinces shows swathes of emerald forest and terraced hillsides have been ripped open, their scars bleeding torrents of mud into valleys below. In North Sumatra, entire neighborhoods in the provincial capital of Medan and Deli Serdang regency lie submerged under a vast sheet of brown water, rooftops barely visible as rivers burst their banks. Roads that once pulsed with traffic now resemble canals, littered with stranded vehicles and uprooted trees.

Rescue workers on Friday were trying to reach many people in isolated villages after floods or landslides damaged roads and bridges, Suharyanto said. Aid and other logistic supplies in some places can be distributed only by foot over the severe terrain,

Rescue teams struggled to reach affected areas in 12 cities and districts of North Sumatra province. while the flooding in West Sumatra also destroyed rice fields, livestock and public facilities.

In Aceh province, authorities struggled to bring excavators and other heavy equipment over washed-out roads after torrential rains sent mud and rocks crashing onto hilly hamlets. 

The extreme weather was driven by tropical cyclone Senyar, which formed in the Strait of Malacca, said Achadi Subarkah Raharjo at Indonesia's Meteorology, Climatology and Geophysical Agency.

He warned that unstable atmospheric conditions mean extreme weather could persist as long as the cyclone system remains active.

“We have extended its extreme weather warning due to strong water vapor supply and shifting atmospheric dynamics,” Raharjo said.

Senyar intensified rainfall, strong winds, and high waves in Aceh, North Sumatra, West Sumatra, Riau, and nearby areas before dissipating. Its prolonged downpours left steep, saturated terrain highly vulnerable to disasters, he 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.

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Karmini reported from Jakarta, Indonesia.

___ The Indonesian disaster agency revised the death toll to 164 after initially reporting 174 deaths, blaming the discrepancy on an error in calculating the death toll in Aceh district, where it lowered the toll to 25.