Video image released by Indonesia's National Disaster Management Agency (BNPB) shows Mount Semeru spewing volcanic materials in Lumajang, East Java, Indonesia, Dec. 4, 2021.Photo:Xinhua

Indonesia's Mount Semeru spewed more ash on Monday, hampering the search for survivors as aerial images showed the extent of the devastation unleashed by the volcano's deadly weekend eruption.

The biggest mountain on the island of Java thundered to life Saturday, ejecting a mushroom of volcanic ash high into the sky and raining hot mud as thousands of panicked people fled their homes. At least 15 were killed.

Aerial photos showed entire streets filled with grey volcanic ash and mud, which had swallowed many homes and vehicles, including whole trucks.

Indonesia's national disaster agency said 27 people were still missing.

"I'm still hoping my son will be found... Every time I hear victims have been found, I hope it is my son," said Maskur Suhri of Sumberwuluh village, who was collecting palm tree sap when Semeru erupted.

"There's a very small chance he survived... Maybe it's my son's fate, but I still hope he will be found, even just his body."

Fresh volcanic activity on Monday hampered search efforts, forcing rescue teams to pull out from some areas.

"There was a small fresh eruption and it could endanger the evacuation teams," said rescue worker Rizal Purnama.

Dangerous thick plumes of smoke continued to emerge from areas blanketed by the volcanic ash, while rescuers in hardhats tried to dig through the mud to try and find survivors - and recover bodies.

Their task was made more difficult as the volcanic debris had started to harden.

"It's very difficult... with simple tools," Rizal Purnama said. "It is very likely bodies that have not been found are buried under the hot mudflow."

Other rescuers helped desperate villagers salvage their belongings from wrecked homes. Some locals lifted mattresses and furniture on their shoulders while others carried goats in their arms.

Officials have advised locals not to travel within five kilometers of Semeru's crater, as the nearby air is highly polluted and could affect vulnerable groups.

Ash from Semeru traveled up to four kilometers away after the Saturday eruption, Indonesia's geological agency reported.

A sand mine company's office in Kampung Renteng village was buried after the eruption, trapping 15 people, according to foreman Hasim, 65, who like many Indonesians goes by one name.

"There's no news from them. Only one operator was rescued, he's now at the hospital with burns," he told AFP.

Hasim said he ran home after the eruption.

"It was pitch dark," he added. "It was only 3 pm but it looked like night."

Rescue officials said some were buried inside their vehicles, with no time to escape.

AFP