Representatives of the protesters had been in talks with the military over who will take control following the ousting of long-time President Omar Al-Bashir.
Negotiations between the two sides have ground to a halt, and the military has scrapped all agreements with the opposition, saying it will hold elections within nine months.
This has angered the protest movement, which had insisted on a transition period of at least three years so it could ensure the elections are free and fair.
How did it all begin?
The unrest in Sudan can be traced back to December 2018, when President Bashir’s government imposed emergency austerity measures in an attempt to stave off economic collapse.
Cuts to bread and fuel subsidies sparked demonstrations in the east over living standards and the anger spread to Khartoum.
The protests broadened into demands for the removal of Mr Bashir – who had been in charge for 30 years – and his government.
The protests reached a climax on April 6, when demonstrators occupied the square in front of the military’s headquarters to demand that the army force the president out.
Five days later, the military announced that the president had been overthrown.
So who is in charge now?
A council of generals assumed power on April 11, but it has struggled to return normality to the country.
The seven-member Transitional Military Council (TMC) is led by Lt-Gen Abdel Fattah Abdelrahman Burhan. The council says it needs to be in charge to ensure order and security.
But the army is not a unified force in Sudan. There are other paramilitary organisations and various Islamist militias that hold some sway.
The military has also faced international condemnation for launching a violent attack on protesters in Khartoum on 3 June which reportedly left at least 100 dead.
The US condemned what it called a “brutal attack” and the UK said the military council bore “full responsibility”.
In response, the TMC expressed “sorrow for the way events escalated”, saying that the operation had targeted “trouble makers and petty criminals” .
Who are the opposition?
The economic problems brought Sudanese from all walks of life to the streets, but the organisation of demonstrations was taken on by the Sudanese Professionals Association (SPA) – a collaboration of doctors, health workers and lawyers.
The protesters are mostly young, reflecting the country’s demographics, but people of all ages have been seen in the crowds.
Women are at the forefront of the demonstrations and a video of a woman who has been named Kandaka, meaning Nubian queen, leading the chants has gone viral.
When the military took power in April, demonstrators stayed put outside its headquarters and insisted that it transfer authority to a civilian administration.
Talks between the ruling generals and the protest organisers, who have come together under the umbrella group Alliance for Freedom and Change, initially showed little sign of progress, but they eventually came to an agreement.
What did the two sides agree?
The military and protesters agreed on 15 May to a three-year transition period to civilian rule.
Demonstrators argue that Mr Bashir’s regime is so deeply entrenched that a long transition is needed to dismantle his political network and allow fair elections.
The two sides also agreed on the structure of a new government – including a sovereign council, a cabinet and a legislative body.
But the military leaders scrapped all of these agreements on 3 June and said fresh elections would be held within nine months.
The TMC’s head said they had decided to “stop negotiating with the Alliance for Freedom and Change and cancel what had been agreed on”.
Former British ambassador to Sudan, Rosalind Marsden, told the BBC that the snap election would “simply pave the way for much of the old regime to come back into power”.
The announcement came shortly after the violent crackdown on protesters in Khartoum.
In the wake of killings, the leaders of the pro-democracy movement said they were cutting all contact with the TMC and called for “total civil disobedience” and a general strike.
What has the international response been?
Most African and western countries have backed the protesters but Saudi Arabia and UAE, who have generally supported the TMC, have urged the two sides to engage in discussions.
The African Union (AU) has suspended Sudan from its membership until a civilian led transitional authority is established.
The UN are removing all non-essential staff from Sudan but China and Russia have blocked moves to impose sanctions.
The US National Security Advisor, John Bolton, condemned the Khartoum violence, calling it “abhorrent”.
But the BBC Africa editor Fergal Keane said this will only mean something if the US demands that its regional allies – Egypt, Saudi Arabia and the United Arab Emirates – exert pressure on the Sudanese military.