The fighting follows days of heightened tensions after the RSF, led by Mohamed Hamdan Daglo, also known as Hemedti, deployed forces across several streets in Khartoum and to the town of Merowe in River Nile State.
Daglo also serves as the deputy chairman of the Transitional Sovereign Council.
Tensions between the SAF and RSF surfaced on Thursday when the army accused the RSF of unauthorized troop movements, calling them illegal and uncoordinated with SAF leadership, as required by procedure.
Despite assurances from both SAF and RSF leaders to civilian mediators on Friday and early Saturday about their willingness to de-escalate, fighting broke out unexpectedly at 9:00 a.m., catching mediators off guard.
The conflict between the two former allies threatens to plunge Sudan into prolonged strife, compounding the challenges of economic collapse and recurring tribal violence.
The unrest comes four years after the ousting of longtime Islamist leader Omar al-Bashir, further destabilizing the fragile transition.