Thirty-seven people accused of illegal mining in north-central Nigeria have died in custody, local officials said.
Police have set up an investigation into the deaths, which the Nigerian Security and Civil Defence Corps (NSCDC) blamed on an apparent disease outbreak.
However, an intelligence report shared with AFP news agency suggested the group died because of overcrowding and poor ventilation inside the detention facility in Niger state.
“We believe they suffocated because there was no ventilation,” the father of one of those detained told the BBC.
Abdullahi Dalhatu said his son had survived because he was near a small window.
“His friend slumped and fainted, and many others also collapsed.”
His son described how detainees began collapsing in the heat of the overcrowded and poorly ventilated cell, his father said.
He said the detainees repeatedly knocked on the door for help but nobody opened it.
State governor Mohammed Umaru Bago called the deaths “sad and tragic” during a press conference on Thursday.
An NSCDC commander has been detained following the deaths, Bago added.
He declared three days of mourning and postponed the start of campaigning for elections scheduled for January.
Officials had arrested the group of young men on Tuesday for suspected illegal mining near Borgu, in the mineral-rich state of Niger. The region is known for small-scale gold mining.
Two days later, 37 people detained as part of the suspected unlawful operation were found dead inside the detention centre run by the NSCDC, a paramilitary agency responsible for protecting critical infrastructure and tackling crimes including illegal mining. It also assists police with internal security operations.
The NSCDC told the BBC that illegal mining was widespread in Niger state, where artisanal miners often operate in open fields.
Its spokesperson, Babawale Afolabi, said more than 50 people were arrested during an operation earlier this week. They had not been charged because profiling and documentation were still under way before the deaths, he said.
“Illegal mining in Niger is serious,” Afolabi said.
The NSCDC had earlier said the detainees were possibly victims of a diphtheria outbreak, a serious bacterial infection that can be fatal.
But the agency’s national headquarters later said the cause had not been established and would require medical and laboratory tests.
“The NSCDC wishes to clarify that reports attributing the deaths to any specific disease remain subject to medical and laboratory confirmation,” it added in a statement.
Dalhatu told the BBC that security officers had been pursuing suspected illegal miners in the community for several days before making arrests.
He said relatives went to the NSCDC office seeking their release but were repeatedly told to return later. “Unfortunately, the following day we got the news that our children had died,” he added.
One father told Nigerian media that his son had appeared healthy when relatives took him food the day before his death and called for an independent post-mortem examination.
Another relative, whose 17-year-old brother was among those who died, said the family had visited him during his detention and questioned how a disease could have killed so many detainees without apparently affecting their guards.
Post-mortem examinations are expected to help establish what happened.
Niger’s police chief ordered an immediate investigation into “the unfortunate death of suspected illegal miners while in the detention facility of the NSCDC”, spokesman Wasiu Abiodun wrote in a statement.
The victim’s bodies have since been taken to the general hospital in nearby Minna for examination.
It is not clear yet whether any of the suspects had been charged.
Nigeria’s constitution requires anyone detained on suspicion of a criminal offence to be brought before a court within a “reasonable time” – generally within a day where a court is available within 40km (25 miles), or two days in other cases, unless a longer period is considered reasonable.
The scramble for gold reserves dug up in illegal mines in Niger state has been blamed for fuelling criminal gang violence, according to officials and experts.
Much of the gold in the region is trafficked through global supply chains, a 2024 SwissAid report found.
