Rescuers detected signs of life in an avalanche of garbage that killed at least four workers and left more than 30 others missing Thursday in Cebu City landfill and plan to intensify search efforts, an official said Saturday.

Twelve workers have been rescued with injuries from the huge mound of garbage that collapsed among the low-slung buildings of a waste management facility in Barangay Binaliw.

Dozens of rescuers, including police, firefighters, and disaster-response personnel, have raced against time to find more survivors in dangerous conditions in the rubble of twisted tin roofs, iron bars, and combustible heaps of garbage and debris.

“Authorities confirmed the presence of detected signs of life in specific areas, requiring continued careful excavation and the deployment of a more advanced 50-ton crane, which is enroute with police escort,” Cebu City Mayor Nestor Archival said in a statement.

“Safety of responders remains paramount due to hazards such as unstable debris and acetylene risks, prompting adjustments to the security perimeter and controlled access,” Archival said.

The four dead, including an engineer and a female office worker, were all employees of the landfill and waste management facility with a staff of 110, according to the mayor and police.

The initial list of victims on Friday included two dead and 36 missing, which increased Saturday to four dead, according to Archival, who did not provide an updated number of people missing.

The cause of the collapse of the mountain of garbage remains unclear, but a survivor said Friday that it happened in an instant without any warning despite fairly good weather at the time.

Jaylord Antigua, a 31-year-old office worker at the landfill, said the wall of garbage cascaded down and destroyed the administrative office he was in. He extricated himself with bruises on his face and arms by crawling in darkness in the rubble and debris.

“I saw a light and crawled toward it in a hurry, because I feared there will be more landslides,” Antigua said. “It was traumatic. I feared that it was my end, so this is my second life.”

It is unclear how the accident would affect garbage disposal in the landfill in Cebu, a bustling port city of nearly a million people that serves as a regional hub for trade, commerce, and tourism.

Preparations “are also underway to manage the looming garbage collection issue," Archival said in his statement without further details.

Such landfills and open dumpsites have long been a source of safety and health concerns throughout the Philippines, especially in areas close to poor communities where many residents scavenge for junk and leftover food in the garbage heaps.

In July 2000, a huge garbage mound in a shantytown in Quezon City collapsed and ignited a fire after days of stormy weather.

The disaster left more than 200 people dead and many more missing, damaged scores of shanties, and prompted a law requiring the closure of illegal dump sites nationwide, as well as improved and more sustainable waste management by authorities. (AP)