The victims - many of whom were children - were found dead on Thursday in the cells of the Nigeria Security and Civil Defence Corps (NSCDC), which had raided suspected illegal gold mines and locked up dozens of miners in the city, the capital of Niger State.
President Bola Ahmed Tinubu ordered an investigation into the deaths after his government earlier suspended some senior officials.
But anger over the incident led to clashes overnight and into Friday.
As the start of curfew approached at 6pm, security forces had restored order to the streets of Minna.
They had earlier used tear gas and fired live rounds as protesters - some armed with sticks, machetes and traditional hunting rifles - called for justice.
A Reuters witness saw one body on the ground.
"We are not thieves. We are simply seeking a way to make a living by mining," Yusuf Auwal, a miner who joined the protesters, told Reuters.
Some protesters had tried to set fire to government buildings in the Tunga neighbourhood.
Niger State governor Umar Bago said many of the dead were children, aged 14 to 18, who had been working in the mines instead of going to school.
"There are issues of illegal mining, and it is taking a toll on our children," he said.
Nigeria's NSCDC security force - an armed agency under the interior ministry meant to protect infrastructure and strategic assets- said the detainees had been held in raids on suspected illegal mines on September 15 and 16 in the Wushishi-Lukoto area west of Minna.
The force, which describes itself as a Federal Government Paramilitary Agency, initially said a disease outbreak may have been involved in their deaths but later said the cause of death had not been established and would be determined by medical examinations.
Survivors said the detainees had been held in a very small cell and died due to extreme heat and a lack of oxygen.
Six survivors told a local television station they had banged on the cell door, but officers did not open it.
"We watched as the victims died gradually," one of them said.
The government on Friday suspended Niger State's NSCDC commandant, Suberu Siyaka Aniviye, and said there would be a full investigation.
Tinubu said any suspensions would not be a substitute for justice and called for any officials found responsible to be prosecuted.
"There must be accountability," he said.
The victims were buried late on Thursday in accordance with Islamic tradition, raising questions about whether or how authorities would carry out further forensic examinations to determine the cause of death.
The mother of one of the detainees, Shafa'atu Suleiman, told Reuters outside the hospital on Thursday that she had visited her son Abdullahi in detention and found him in a cramped NSCDC cell, before later learning that he had died.
Officials had refused to allow relatives to deliver food to the detainees and demanded 100,000 naira ($A105) for them to be freed, she said.
"This is injustice. We will not forgive them."
NSCDC officials did not respond to multiple requests for comment on her accusations.
Nigeria has tried for years to curb unauthorised mining at thousands of informal sites that operate across the country.
The authorities say illegal mining damages the environment and leads to losses of government revenue.
Tinubu said on Friday the government would continue its crackdown on illegal mining but called for any actions to be conducted lawfully.
with DPA
