Thousands of demonstrators vowed to stay on the streets of the Sudanese capital, Khartoum, despite a curfew imposed by the country's new military council.
Long-time President Omar al-Bashir was overthrown and arrested Thursday after months of street protests.
But protesters say the military council is part of the same regime.
The renewed dispute has aroused the fear of a violent confrontation between the demonstrators and the army.
There is also a real danger that various elements of the security forces and the militias could line up their weapons, says BBC World Service Africa editor Will Ross.
The UN and the African Union have both called for silence.
An atmosphere of The Celebration following the news of the arrest of Mr. Bashir, 75, was quickly fading as the organizers of the demonstrations demanded that a seat outside the military headquarters be held.
"This is a continuation of the same regime," said Sar Abdeljalil of the Sudanese Employers' Liability Insurance Association. "So we have to continue the fight and the peaceful resistance."
- Sudan's riots in 300 words
- Bashir was overthrown: Five major moments
Later was presented in an official statement by state media A curfew runs from 22:00 local time (20:00 GMT) to 04: 00 o'clock.
"Citizens are advised to stick to it for their safety," he said, adding, "The armed forces and the Security Council will live up to their duty to safeguard peace and security and protect the livelihood of their citizens."
Crowds on the streets of Khartoum waved flags and sang "Fall Again!" ̵
Mr. Bashir is the subject of an international arrest warrant by the International Criminal Court (ICC), which accuses him of organizing war crimes and crimes against humanity in Sudan's western Darfur.
It is not clear what will happen to him in his detention.
How did the coup d'état develop?
Military vehicles entered Khartoum's large grounds on Thursday housing the Department of Defense, Army Headquarters and Mr. Bashir's personal residence.
State television and radio broke programming and defense minister Awad Ibn Ouf, who announced "the overthrow of the regime." He said that Mr. Bashir was being held "in a safe place," but he did not give any details.
Mr Ibn Ouf said the country was under "bad management, corruption and an absence of justice" and he apologized "for the killing and violence that took place."
He said the army would become one supervise two-year transitional period with subsequent elections.
- Are military takeovers in Africa on the rise? 19659031] The minister also said that a three-month state of emergency would be introduced.
The Sudanese constitution was suspended, the border crossings closed until further notice and the airspace closed for 24 hours, he added.  "An Unstable and Unpredictable Situation"
This is a military coup without a clear roadmap as the generals plan to transfer power to civilian rule.
The fear will be that they have no such intention. The security elite has calculated that removing Omar al-Bashir and imposing a curfew will give them time and stop the protests. If so, this is a grave miscalculation.
The Sudanese Professionals Association (SPA) – which led the demonstrations – and other civil society groups have made it clear that they will not accept cosmetic changes. They have the numbers and are well organized.
The military has the weapons and the ability to enforce brutal repression. But what then? A crackdown will not solve the desperate economic crisis that last year brought scorching resentment on the streets for years.
There is also the question of the cracks within the Sudanese security organization that were evident during the clashes between soldiers and intelligence services / militias in recent days. It is a volatile and unpredictable situation that requires cool minds and compromises from the military. The stability of Sudan depends on how it reacts to ongoing protests.
How did the demonstrators react?
The SPA said the military had announced a "coup" that merely reproduced the same "faces and institutions that our great people revolted against".
It urged people to continue the session – outside the military complex – which began on Saturday – and to be on the streets of cities across the country.
"Those who destroyed the land and killed people try to steal every drop of blood and sweat from the Sudanese. People poured into their revolution, which shook the tyranny's throne," the statement read.
The SPA has previously said that any interim administration may not include anyone from the "tyrannical regime".
How did the protests begin?
The demonstration started in December. They were originally triggered by a rise in the cost of living, but then the masses demanded the resignation of the president and the government.
Government officials said 38 people have died since December, but Human Rights Watch said the number is higher.
In February, it looked like the president could step down, but instead, Mr. Bashir declared the national emergency.  19659023] What international reaction was there?
UN Secretary-General Antonio Guterres called for "the calm and extreme restraint of all" and urged for a transition that would meet the "democratic aspirations" of the people. The UN Security Council will discuss the situation in a closed session on Friday.
Foreign Minister of Britain Jeremy Hunt said a two-year military council was "not the answer" .
"We need a quick step towards inclusive, representative civilian leadership and we need to make sure that there is no more violence," he said on Twitter.
The US called on the Sudanese military to bring civilians into the transitional government, saying that a two-year timeline was too long.
The African Union condemned the military takeover. Moussa Faki Mahamat, chairman of the AU Commission, said this was not an appropriate response to the country's challenges and aspirations of its people.
Russia, which twice hosted Mr. Bashir, demanded calm and said the situation was under surveillance. 19659007] Amnesty International Secretary-General Kumi Naidoo said justice was "long overdue" for Mr Bashir.
"Omar al-Bashir is being sought for some of the most outrageous human rights abuses of our generation and we must finally hold him accountable," Naidoo added.
Who is Omar al-Bashir?
The former military officer seized power in 1989 in a military coup.
His reign was marked by a civil war. The civil war with the south of the country ended in 2005, and South Sudan became independent in 2011.
Another civil war has taken place in the western region of Darfur. Mr. Bashir is accused of organizing war crimes and crimes against humanity there by the ICC.
Despite an ICC international arrest warrant, he won consecutive elections in 2010 and 2015. His last victory, however, was hampered by a boycott of boycott the main opposition parties.
The warrant has led to an international travel ban. However, Mr. Bashir has made diplomatic visits to Egypt, Saudi Arabia and South Africa.