At least 34 people have died following the eruption of the highest volcano on the island of Java.
Officials said around 17 others remain missing after Saturday's eruption on Indonesia's most densely populated island.
National Disaster Mitigation Agency spokesperson Abdul Muhari had said on Sunday at least 14 villagers died from severe burns and 56 others were hospitalised, including 41 with burn injuries.
But the number of casualties has arisen as rescue efforts continued amid improving weather conditions.
Indonesia’s president Joko Widodo visited areas in the Lumajang district devastated by the eruption on Tuesday and vowed that communities would be quickly rebuilt.
The Indonesian Red Cross has warned that the death toll in the island's mountainous areas is expected to rise further.
Several villages 'turned to darkness'
Heavy rains triggered a sudden eruption of Mount Semeru in East Java province on Saturday, spewing thick columns of ash more than 12,000 meters into the sky.
Villages and nearby towns were blanketed by tons of volcanic debris as searing gas and lava flowed down the slopes. Nearly 3,000 houses and 38 schools were damaged, according to Muhari.
"Thick columns of ash have turned several villages to darkness,” said Lumajang district head Thoriqul Haq.
Several hundred people were moved to temporary shelters or left for other safe areas, he said, adding that a power blackout had hampered the evacuation.
The debris and lava mixed with rainfall formed thick mud that destroyed the main bridge connecting Lumajang and the neighbouring district of Malang, as well as a smaller bridge, Haq stated.
The Lumajang district administration has declared a month-long emergency until January 3.
Questions over warning system
Despite an increase in activity since Wednesday, Semeru’s alert status had remained at the third-highest of four levels since it began erupting last year.
He said rescuers were still searching for several residents and sand miners along a river in Curah Kobokan village who were reported missing.
Entire houses in the village were damaged by volcanic debris and more than 900 people fled to temporary government shelters, Muhari said.
Liswanto, the head of Semeru’s monitoring post, said his office had informed the community and the miners that hot ash could tumble down from Semeru’s crater at any time after sensors picked up increased activity in the past week.
But some residents who fled to a government shelter near Lumajang district's head office said authorities did not convey any information to them about the volcano's activities.
"Suddenly everything went dark, the bright afternoon turned into night," said Fatmah, a resident who fled to the shelter from Curah Kobokan, about 5 kilometres from the crater.
"A rumbling sound and heat forced us to run to the mosque ... It was a far stronger eruption than in January," he said.
Meanwhile, cargo planes carrying food, tents, blankets, and other supplies landed on Tuesday for temporary shelters crammed with about 3,700 displaced people.
Transportation Ministry spokesperson Adita Irawati said her office issued a notice on Saturday for all airlines to avoid routes near the volcano.
She said flight operations are still running as scheduled and that authorities will continue to monitor the situation.
Indonesia, an archipelago of more than 270 million people, is prone to earthquakes and volcanic activity because it sits along the Pacific "Ring of Fire," a horseshoe-shaped series of fault lines.
The last time Semeru erupted, in January, there were no casualties.