GUSAU, Nigeria (AFP) — Rescuers in Nigeria are searching for dozens of people missing after a boulder crashed onto an illegal mine during heavy rains, killing at least 18 people, local sources told AFP on Saturday.

The rock came crashing down on Thursday on the mine in the northern Zamfara state outside the Kadauri village in the Maru district, they said.

“We have managed to pull out 18 dead bodies from the pit and five other survivors who sustained various degrees of injuries,” Sani Lawwali, a miner who works in unauthorised pits, said from Kadauri.

A dozen other miners were still trapped inside and their fate remained unknown, said Lawwali, who took part in the rescue effort.

“The process is slow and laborious as we use our bare hands to chisel the end of the boulder to make holes for limited access into the pit,” he said.

Rescuers have asked for a bulldozer being used at a nearby road construction site to be brought in to help, but had not yet received a response from the company using it, Lawwali added.

Abubakar Nabube, a local community leader, confirmed the death toll of 18. He said that 15 of those killed came from the nearby Maikwanugga and Damaga villages.

“If no help comes from emergency agencies soon, none of those trapped would come out alive,” he said.

Zayyanu Ibrahim, a resident of Kadauri village said the collapse occurred at one of several newly dug sites in the recently established mining site.

“Dozens of miners were working in the pit while it heavily rained outside. A huge boulder at the mouth of the pit collapsed and buried miners inside,” said Ibrahim, who also confirmed the toll.

Sani Abdullahi, a councillor in the area, said it was difficult to say how many people there were in the pit at the time of the accident.

Officials from the Nigerian emergency agency NEMA did not respond to an AFP enquiry about the accident.

Zamfara, a poor agrarian state, is rich in gold deposits where illegal artisanal mining thrives in the countryside, despite several attempts by authorities to stop the practice.

The authorities have blamed illegal mining for the worsening of bandit violence, with criminal gangs getting money from protection fees they extort from miners.