Sudanese security troops fired tear gas and stun grenades and used live rounds to disperse tens of thousands of protesters who gathered in the capital Khartoum on Wednesday to rally against military rule.
Similar demonstrations took place in cities across the nation.
At least one protester, Al Tayeb Nasser, 19, was killed when he was hit by a live round in the Khartoum suburb of Sharq El Neel, medics said.
About 76 others were injured in the capital, including four by live rounds, they said.
The rallies, named “The earthquake of April 6” by pro-democracy groups, were met by thousands of police across the Sudanese capital.
Security forces closed Khartoum’s Nile bridges and increased their presence around locations where protesters were likely to assemble, such as the Republican Palace, the army headquarters and the Parliament building.
Wednesday's protesters braved heat and, for most, the hunger and thirst from Ramadan fasting.
Many broke their their fast at sunset on the streets, eating dates and drinking water and fruit juice distributed by organisers.
"April 6 is a special day but will not be the end of the road," said one Khartoum protester, physician Waleed Suleiman, 36.
"But any movement on the streets must be accompanied by political action to bring about results. That action requires the unity of all political forces."
The government declared Wednesday a national holiday, a tactic aimed at isolating the protesters from the rest of the city's residents, who will be staying home.
By noon there was hardly anyone on the streets in central Khartoum and most shops closed. Temperatures rose to 42ºC and hit 45ºC later in the afternoon.
But the number of the protesters on the streets grew as the heat began to wane by the afternoon.
They waved Sudanese flags, singing and chanting "the people want to bring down the regime" and "the soldiers back to their barracks".
Protesters circumvented the closure of most Nile bridges by taking longer routes to central Khartoum or crawling under the shipping containers used by security forces to block the bridges' entrances.
"We want a Sudan free of pain and destruction," said protester Hayam Babikr, 32. "My message to those who selected to stay home today is to come out and join us. Our unity will realise our dreams."
Despite the security measures, the Resistance Committees, the grass-roots pro-democracy group leading the near-daily protests against military rule since army chief Gen Abdel Fattah Al Burhan seized power last October, was defiant.
“The earthquake of April 6 will come as a spear in the chest of the tyrants and a giant leap towards the change we aspire to,” the Resistance Committees said on Tuesday night.
“We enter this battle while the revolutionaries' dream has drawn closer. The people will come out tomorrow on the earthquake of April 6 and not return home until the dawn of eternal salvation arrives.”
The committees ordered protesters in Khartoum to leave the streets and head to their homes by 9pm.
"You have written the history and the end of the coup, which will inevitably be defeated," it said.
There were also anti-military rallies on Wednesday in the eastern Sudanese cities of Gedaref, Kassala and Port Sudan, as well as Wad Madani, Kosti and Kadugli to the south of the capital.
The western cities of Nyala, Obeid and Geneinah also saw street protests.
Wednesday's rallies mark two milestone events in contemporary Sudanese history that led to the removal of dictators.
They were an uprising in 1985 that toppled the 16-year rule of military dictator Jaafar Al Nimeiri, and the start of a sit-in outside the army headquarters in 2019 calling for the removal of Omar Al Bashir.
Army generals removed Al Bashir on April 11 that year, but the protesters continued their sit-in to press demands that the military hand over power to civilians.
On June 3, security forces violently broke up the sit-in, killing at least 128 protesters.
Two months later, the pro-democracy movement and the military reached a transitional power-sharing deal, which Gen Al Burhan discarded when he seized power only weeks before he was to hand over to a civilian his position as de facto head of state.
An investigation into the break-up of the sit-in has yet to publish its findings more than two years after it began its work.
And little is known about the fate of investigations ordered by Gen Al Burhan into the killing of protesters since his takeover and alleged sexual assault by security forces of female protesters.
At least 93 protesters have been killed and about 3,000 injured since the coup, in a wide crackdown against the opposition that includes arbitrary detentions and forced disappearances of activists.
US State Department spokesman Ned Price On Tuesday called on Sudan's military rulers to allow the peaceful protests "to continue without fear of violence".
The large Umma party, meanwhile, joined the pro-democracy groups in calling for the Sudanese to rally on Wednesday.
“There is no excuse for anyone who refrains from taking part in the rallies of national salvation,” it said.
Gen Al Burhan’s October 25 coup derailed Sudan’s democratic transition and plunged the country into its worst economic crisis in decades.
Western powers suspended aid to Sudan worth hundreds of millions of dollars and shelved a debt forgiveness programme.
The UN says the number of people in Sudan facing extreme hunger will double to 18 million by September because of the political deadlock, poor harvests, and worsening security.
It said the country was heading towards "economic and security collapse" and significant humanitarian suffering if the political crisis was not swiftly addressed.
Gen Al Burhan said on Saturday that he would hand over power only to an "honest, elected authority accepted by all the Sudanese people".
He suggested that the pro-democracy movement was a tool in the hands of Sudan’s foreign enemies, and equated criticism of the military with treason.
On Wednesday, Reuters reported that factions allied with the military had drawn up a deal to cement the generals' grip on power and exclude the civilian parties and pro-democracy groups.
There was no comment immediately available from the military.
Meanwhile, most Sudanese are unable to make ends meet in the face of rising prices of essential food items and fuel.
The value of the pound has also plummeted against the US dollar, and power failures have become more frequent at a time of year when the temperature routinely climbs above 40°C.
Hundreds dead or hurt in Darfur
Violence has frequently broken out in recent months in the troubled Darfur region between Arab and non-Arab groups, leaving hundreds of people dead or injured.
The latest bout was on Thursday, when fighting killed 45 people in South Darfur.
In the early 2000s, ethnic Africans in Darfur rebelled against perceived discrimination by the Arab elite in northern Sudan.
It was brutally put down by government forces backed by local Arab militias. Al Bashir and several of his associates have been indicted for war crimes, genocide and crimes against humanity by the International Criminal Court in The Hague.
A militia commander, Ali Mohammed Ali Abdel-Rahman, 72, appeared before the court on Tuesday facing 31 counts of war crimes and crimes against humanity committed in Darfur in 2003 and 2004.
Abdel-Rahman was the first to be tried by the ICC in a Darfur-linked case.