Hours of heavy downpours resulted in landslides on Thursday night in Sumber Wuluh village, Candipuro district, Lumajang. Three meters of mud and dislodged vegetation covered a key stretch of road in the district.

Hours later, landslides swept through the neighboring Pronojiwo district, killing a family of three, consisting of a husband, wife and their 4-month-old son.

At around 10 a.m., three rivers in Lumajang – the Besuk Bang, Besuk Sang and Besuk Kobokan – breached their banks. All three run from Mount Semeru, an active volcano, and overflowed with lahar.

This destroyed a further six bridges in the regency, including the Kaliglidik bridge, which connects Lumajang to neighboring Malang regency. It also left the districts of Pronojiwo and Tempursari temporarily cut off from aid.

Although lahars typically occur during volcanic eruptions, they can also be triggered by the erosion of volcanic ash deposits during heavy rains.

The string of disasters prompted the Lumajang administration to declare a two-week state of emergency on Friday, as emergency supplies and disaster relief services poured into the area.

According to data from the National Disaster Mitigation Agency (BNPB), a total of 571 residents had moved to one of 13 shelters as of Saturday morning, although the number is expected to climb as search-and-rescue work continues.

The Lumajang Disaster Mitigation Agency (BPBD) reported on Saturday that it had managed to reopen the road connecting Lumajang Malang.

“On [Saturday] afternoon we managed to reopen the [Lumajang-Malang] road, which was previously completely covered in landslide [debris]. Now, two-wheeled and four-wheeled vehicles can pass," BPBD Lumajang acting head Patria said.

More than 135 personnel from the East Java Social Affairs Agency and East Java Disaster Mitigation Agency have been deployed to Lumajang to aid in disaster relief efforts.

“The Social Affairs Agency has also sent its [food] stock to help start temporary soup kitchens, as well as sleeping equipment for 30 families,” Governor Khofifah Indar Parawansa said on Saturday, as quoted by Kompas.id.

The East Java Health Agency, Khofifah said, had also sent medications to shelters in Candipuro and Pronojiwo and had dispatched doctors and nurses to check on affected residents.

Coordinating Human Development and Culture Minister Muhadjir Effendy, who was in Lumajang on Saturday to inspect the emergency relief efforts, said part of the reason for the high number of displaced people was that many had refused to move out of Mount Semeru’s “hazard zone” into to newly built houses further from the volcano.

“There were a handful families who should have moved [away from Mount Semeru long ago] but refused to relocate,” Muhadjir said on Saturday, as reported by Antara. “They were still living in the hazard zone of Mount Semeru.”

The Meteorology, Climatology and Geophysics Agency (BMKG) has forecast that East Java will experience increased levels of rainfall until Aug. 13.