LAGOS, Nigeria (AP) — Nigerian protesters demanding an end to police brutality defied a curfew and faced off with security forces Wednesday as gunfire rang out and fires burned in Lagos, a day after shots were fired into a crowd of demonstrators singing the country’s national anthem.

It’s not clear if any protesters were killed in Tuesday night’s shooting at the Lekki toll plaza in the West African country’s sprawling commercial capital. Lagos' governor said many were injured but no one was killed, although Amnesty International and the U.N.’s high commissioner for human rights both said people died and that security forces were responsible. The military has denied it was responsible.

Gunfire reverberated across Lagos on Wednesday, including at the Lekki toll plaza, where young demonstrators were rallying again despite an order for everyone to stay off the streets until further notice. At the sound of the shots, some protesters could be seen running away, though it wasn’t clear if the crowd was fired upon.

Police also fired tear gas at one point, and smoke could be seen billowing from several areas in the city’s center. Two private TV stations were forced off the air at least temporarily as their offices were burned.

Demonstrations and gunfire were also reported in several other Nigerian cities, including the capital city, Abuja.

Young people have taken to the streets for more than two weeks after anger over heavy-handed policing flared in response to a video of a man being beaten, apparently by officers with the Special Anti-Robbery Squad, known as SARS.

In response to the #EndSARS movement, the government announced it would disband the unit, which Amnesty International says has been responsible for many cases of torture and killings. But that has failed to satisfy demonstrators, who are now demanding more widespread reforms to end human rights abuses committed by security forces of all stripes and pervasive government corruption.

Though Nigeria has massive oil wealth, and is one of Africa’s largest economies, many of its 196 million people face high levels of poverty and lack of basic services — because of rampant graft, according to rights groups. Nigerians have flooded Twitter in recent weeks with accounts of the everyday indignities and outright abuse they face, from being regularly shaken down by police for bribes to beatings and even killings.

But their demands for better governance drew new attention both inside and outside the country after videos were posted on social media in which gunfire could be heard echoing over protesters as they sang the national anthem at the Lekki toll plaza in the darkness Tuesday night. After the shots, people can be heard running away.

It’s not clear in the videos who was firing, but some are pointing the finger at Nigeria’s military. U.N. High Commissioner for Human Rights Michelle Bachelet made the clearest accusation, saying that “there is little doubt that this was a case of excessive use of force, resulting in unlawful killings with live ammunition, by Nigerian armed forces.”

She noted that there were reports — not yet confirmed — that security cameras were disabled and lights turned off before the shooting began, moves that would indicate a “deplorable,” premeditated attack. She called for “a root and branch re-examination of the entire security sector” to address yearslong complaints of violence.

Amnesty International has said it has “credible but disturbing evidence” that security forces were to blame for the Lekki plaza shooting, while the Lagos governor has ordered an investigation into the actions of the military there.

No one has said how many people were killed, and Gov. Obajide Sanwo-Olu has denied there were any fatalities, confirming instead that 25 people were injured. He said he went to mortuaries and did not find any bodies.

“This is the toughest night of our lives as forces beyond our direct control have moved to make dark notes in our history, but we will face it and come out stronger” the governor tweeted earlier Wednesday.

He had also warned on Twitter that the protests against police brutality had “degenerated into a monster that is threatening the well-being of our society.”

Nigeria’s military, however, denied responsibility for the Lekki shootings, posting a tweet that labeled several reports as fake news.

President Muhammadu Buhari — who has said little about the protests engulfing his country— did not mention the Lekki shootings but in a statement Wednesday issued a call for calm and vowed police reforms.

Buhari’s statement said the dissolution of the SARS unit “is the first step in a set of reform policies that will deliver a police system accountable to the Nigerian people.”

Nigeria’s spiraling crisis has drawn international attention, and foreign dignitaries and celebrities, including U.N. Secretary-General Antonio Guterres, U.S. presidential candidate Joe Biden and Beyoncé, have denounced the shootings.

Before the shootings at Lekki, Nigeria’s police statement warned that security forces would now “exercise the full powers of the law to prevent any further attempt on lives and property of citizens.”

The Lekki shootings come after two chaotic weeks of social unrest. On Tuesday, authorities said nearly 2,000 inmates had broken out of jail after crowds attacked two correctional facilities a day earlier.

The Inspector-General of Police said it was deploying anti-riot police across Nigeria and ordered forces to strengthen security around correctional facilities.

The curfew in Lagos began Tuesday afternoon and most businesses and shops are closed across the city, but the demonstrators are erecting barricades in the streets. The curfew was announced after a police station was burned down in the city and two people were shot dead by police.

Lagos has been the center of the protests, with demonstrators at times blocking access to the airport and barricading roads leading to the country’s main ports.

Nigeria's Nobel prize-winning author Wole Soyinka described how his elation at seeing the young protesters demanding a better Nigeria turned to horror as they were shot.

“The army must apologize, not merely to the nation but to the global community – the facts are indisputable – you, the military, opened fire on unarmed civilians,” Soyinka wrote on Wednesday.

Soyinka said he spoke with many of the protesters at roadblocks and warned of their growing fury, urging the government to negotiate a resolution.

“Do not attempt to dictate — Dialogue!” he wrote.

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Associated Press journalist Bashir Adigun in Abuja, Nigeria, contributed.