Gunfire could be heard as people ran through streets of Lagos while plumes of smoke rose from a prison on Thursday.
Signs of unrest persist in Nigeria, which has been gripped by protests against police brutality.
It is not clear what was happening at the Ikoyi Correctional Centre, known for its overcrowded cells holding people awaiting trial.
Prisons and police stations have been broken into over the past two weeks as anger at authorities boiled over and some sought to take advantage of the protests to create mayhem.
Officials did not immediately comment on the situation at the prison.
Elsewhere in the sprawling city of 14 million, the streets were almost empty and shops were closed as residents largely obeyed a government curfew meant to curb the chaos.
For two weeks, protesters have taken to the streets peacefully but on Wednesday mobs vandalised and burned police stations, courthouses, TV stations and a hotel.
Smoke billowed from several locations in the city as police battled angry crowds with tear gas and gunfire.
Some protesters active on social media disavowed the violence, saying their demonstrations had been hijacked by criminals.
Wednesday’s violence came a day after security forces fired into a crowd of thousands of protesters, according to Amnesty International, killing 12.
At least 56 people have been killed during the protests, Amnesty said.
That shooting drew outrage and brought new attention from around the globe to the protests.
The #EndSARS demonstrations began in early October with calls for Nigeria’s government to shut down the police Special Anti-Robbery Squad, known as SARS.
The government has agreed to disband the unit but the protesters have now broadened their demands to include more widespread reforms to end human rights abuses and political corruption.
President Muhammadu Buhari – who has said little about the protests engulfing his country – did not mention the Lekki shootings in a statement on Wednesday but issued a call for calm and vowed police reforms.
UN Secretary-General Antonio Guterres said the right of Nigerians “to protest peacefully needs to be guaranteed”.
He said “police brutality needs to stop and those responsible for acts of such dramatic violence are made accountable”.
Mr Guterres said he spoke to Mr Buhari several days ago and believes he “will be able to bring things into a normal way to respect the rights of assembly of people and to make sure that those that misbehaved are held accountable”.