At least 37 people detained on suspicion of illegal mining have died while in the custody of Nigeria’s civil defence agency in Niger State.
The detainees died after being arrested during operations targeting suspected illegal mining on Tuesday and Wednesday.
The Nigeria Security and Civil Defence Corps (NSCDC) said a suspected disease outbreak may have caused the deaths.
However, the exact cause remains under investigation.
Survivor describes overcrowded cell
A survivor, Dauda Shehu, gave a different account of the conditions inside the detention facility.
Shehu told AP that 65 detainees had been held in a poorly ventilated cell.
He said those inside struggled to breathe and tried to attract the attention of guards.
The account has raised questions about whether overcrowding and poor ventilation contributed to the deaths.
However, authorities have not yet established the cause.
Medical examinations ordered
Niger State NSCDC Commandant Suberu Siyaka Aniviye said the bodies were taken to a local hospital for medical examinations.
The examinations are expected to help determine what caused the deaths.
Meanwhile, Niger State police have opened an investigation and asked relatives of the victims to provide any information that could assist the inquiry.
Niger State Governor Mohammed Umaru Bago described the deaths as tragic and announced three days of mourning.
The state government has also established a committee to investigate the incident.
Investigation continues
The deaths have drawn further scrutiny of the circumstances in which the detainees were held.
The federal government has suspended the Niger State NSCDC commandant while an investigation takes place.
For now, authorities have not announced a confirmed cause of death.
The investigation and medical findings are expected to provide more information about what happened inside the detention facility.