Nigerian security forces fired at protesters and used tear gas during demonstrations over the deaths of 37 miners who died while in police custody in Niger State.
Hundreds of people took to the streets for a second consecutive day on Friday in Minna, the state capital, with some protesters attacking government facilities.
It was not immediately clear whether security forces used live ammunition or anti-riot pellets. However, a witness told Reuters that bullets were fired and that the body of one person was seen lying on the ground.
Authorities announced Thursday that 37 miners had died while being held by the Nigeria Security and Civil Defence Corps (NSCDC), a paramilitary agency. The miners had been arrested earlier this week during raids in the Wushishi-Lukoto area, west of Minna, over alleged illegal mining.
Niger State Governor Umar Bago imposed a 24-hour curfew on Friday as the government pledged a full investigation into the deaths.
Al Jazeera reporter Ahmed Idris said the violence mainly targeted government facilities in Minna and eased after the curfew was imposed. A transport agency was among the facilities attacked, with buses and other vehicles damaged.
The NSCDC initially said the miners may have died from an outbreak of disease but later said the cause of death had not been established. It said further investigations, including medical examinations, would be conducted.
However, all the bodies were buried Thursday evening, raising questions about whether post-mortems can still be carried out.
AFP reported that an intelligence report it had seen suggested poor ventilation and overcrowding in the cells may have caused the deaths. Some protesters also told the Associated Press that the miners had suffocated.
Survivors described struggling to breathe inside the overcrowded cell. Dauda Shehu told journalists at a central Nigerian hospital that there was little ventilation and detainees repeatedly appealed for fresh air and banged on the cell door, but received no response.
The NSCDC's Niger State commandant, Suberu Siyaka Aniviye, has been suspended by Interior Minister Olubunmi Tunji-Ojo pending the investigation.
The Interior Ministry described the incident as unfortunate and said a full investigation would be conducted.
Niger State has large deposits of minerals, including gold and uranium, while mining plays a major role in its economy.
Source: Al Jazeera