At least 40 people were killed in an airstrike on a market in southern Khartoum, the local volunteer emergency room said in a statement on Sunday.
According to international media reports, it is the largest single-incident civilian death toll of the civil war in Sudan that began on April 15, as fighting in residential areas intensifies.
"The number of victims of the Quoro market massacre" had risen to 40 three hours after the raid, the committee said, after initially giving a death toll of 11.
The committee said the toll was expected to rise further, as casualties continued to arrive at Bashair hospital.
The hospital had issued an "urgent appeal" for all medical professionals in the area to come and help treat the "increasing number of injured people arriving".
Since April 15, Sudan has been gripped by a devastating war pitting the regular army, led by Abdel Fattah al-Burhan, against the paramilitary Rapid Support Forces, commanded by his former deputy Mohamed Hamdan Daglo.
Nearly 7,500 people have been killed, according to a conservative estimate from the Armed Conflict Location & Event Data Project.
The real death toll is presumed to be much higher, with many of those wounded and killed never reaching hospitals or morgues.
Access to many areas has been cut off completely and the warring sides have not declared their losses.
Nearly five months in, neither side has been able to seize a decisive advantage.
The armed forces control the skies over Khartoum, while RSF fighters continue to dominate the city's streets.
The army has been accused of repeated indiscriminate shelling of the residential areas where the paramilitaries have embedded themselves, including by evicting families and taking over homes.
