Gangs armed with knives and sticks blocked major roads in Lagos, with many on the streets angered by a speech in which the president called for calm but failed to condemn the killing of protesters demanding an end to police brutality.
The unrest is the worst street violence since Nigeria's return to civilian rule in 1999 and the most serious political crisis confronting President Muhammadu Buhari, a former head of a military regime who came to power at the ballot box in 2015.
A highway leading to the international airport was obstructed on Friday by blockades manned by groups of young men demanding cash from motorists. Petrol stations were closed and cash machines were not working in parts of the city.
Violence in Nigeria's sprawling commercial hub, a city of 20 million, has escalated since Tuesday night, when a round-the-clock curfew was announced.
Why are Nigerians protesting?
Amnesty International said soldiers and police killed at least 12 protesters on Tuesday in Lekki and Alausa, two Lagos districts. On Thursday, Amnesty, Human Rights Watch and 40 other groups demanded an immediate and thorough investigation of the incident.
A Nigerian DJ and musician known as DJ Switch, who broadcast the shooting in Lekki live on Instagram, on Friday recounted the incident on the social media platform. She said the military carried out the shooting and she counted 15 dead bodies.
The army has denied soldiers were at the site of the shooting, where people had gathered in defiance of the curfew.
Mr Buhari, in a national address late on Thursday, urged youths to "discontinue the street protests and constructively engage government in finding solutions".
It was his first public address since the shootings. He lamented the loss of innocent lives, but did not directly refer to the Lekki incident that sparked international condemnation.
Protests in London and New York over Nigerian police brutality
Many of those on the streets despite the curfew said Buhari's speech had angered them by his failure to address the fatal shooting of protesters.
"We expected him to say something to condemn the killing," said businessman Lekan Shonibare.
Lagos authorities have struggled to enforce the curfew as anger over the killings rose.
The violence and destruction that led to buildings being burned across the city meant many locals felt trapped.
"I feel it's not safe. We have had cases of people looting and destroying properties," said Cynthia Kazuo, a resident of the city's Yaba district who said she heard prolonged bursts of gunfire outside her home in recent days.
The state government said on Friday the restrictions on movement would be eased from Saturday, with the curfew in place from 6pm to 8am.
"Our beautiful city has seen a level of destruction almost akin to a war zone. It was a shocking and very sad spectacle," Lagos State Governor Babajide Sanwo-Olu wrote on Twitter on Thursday.
Disruption has not been limited to Lagos. Several states in southern Nigeria have imposed curfews after two weeks of confrontations between security services and protesters.
In addition to anger within Nigeria at the shooting of demonstrators, the incident has prompted a wave of international criticism of Nigerian authorities and the behaviour of the security forces.
A delegation of US officials who were in Nigeria for previously scheduled meetings met the country's vice president on Thursday and condemned the "use of excessive force by military forces who fired on unarmed demonstrators in Lagos", a State Department spokeswoman said.
In his address, Buhari said the international community should "know all facts available" before rushing to judgment.
