It is the fourth effort to stop the fighting which began on 15 April in sudan, with previous truces not observed.
US Secretary of State Antony Blinken said the 72-hour truce had been agreed between the army and the paramilitary Rapid Support Forces (RSF) after 48 hours of negotiations.
The latest ceasefire attempt started at midnight (22:00 GMT on Monday).
There have also been reports of warplanes flying over Khartoum, but civilians are back on the streets of the capital.
Both sides in the conflict, which has left more than 400 people dead, independently announced their involvement in the ceasefire.
Despite the agreement, Tagreed Abdin, who lives 7 kilometers from Khartoum’s center, claimed she could hear shelling on Tuesday morning from her house.