MINNA, Nigeria: Security forces opened fire in the central Nigerian city of Minna on September 18 as hundreds of people protested the deaths of 37 detainees in the custody of a paramilitary force, witnesses said.

The bodies were found a day earlier in cells belonging to the Nigeria Security and Civil Defense Corps (NSCDC). The agency had raided suspected illegal gold mines and detained dozens of miners in Minna, the capital of Niger State.

The government has promised to investigate the deaths and has suspended some senior officials. However, anger over the incident led to clashes overnight and continued into Friday.

An eyewitness saw security forces fire live rounds as protesters, some carrying sticks, machetes and traditional hunting rifles, demanded justice. Some protesters also tried to set fire to government buildings in the Tunga neighborhood.

"We are not thieves - we are simply seeking a way to make a living by mining," miner Yusuf Auwal, who joined the protest, told Reuters.

At least one body was seen lying on the streets. Soldiers and police officers were deployed across Minna as authorities tried to restore order.

The agency said the detainees had been arrested during raids on suspected illegal mines in the Wushishi-Lukoto area, west of Minna, between September 15 and 16.

The NSCDC initially said a suspected disease outbreak could have been linked to the deaths. It later said the cause of death had not been established and would be determined through medical examinations.

Interior Minister Olubunmi Tunji-Ojo ordered the immediate suspension of Niger State NSCDC commandant Suberu Siyaka Aniviye pending a full investigation.

"It is an unfortunate incident; however, a full investigation will be conducted while the commandant under whose watch this happened remains suspended," the Interior Ministry said in a statement.

Anger over the deaths led to protests in Minna on the night of September 17. Residents said young people chanted for justice, while some protesters damaged vehicles.

The city was calm by the morning of September 18, but security forces had been heavily deployed in parts of Minna.

Nigeria has been trying for years to stop illegal mining at thousands of informal sites across the country. Authorities say illegal mining causes environmental damage and reduces government revenue.