Artillery fire could be heard in parts of Khartoum and warplanes flew overhead on Tuesday, residents said, though an internationally-monitored ceasefire appeared to have brought some respite from heavy fighting in the Sudanese capital.
Night-time airstrikes were reported in at least one area after the ceasefire started late on Monday, but residents otherwise reported relative calm.
The truce was agreed at talks in Jeddah on Saturday after five weeks of fierce battles between the army and the paramilitary Rapid Support Forces (RSF). It is being tracked by Saudi Arabia and the United States and is meant to allow for the delivery of humanitarian relief.
Sudanese activists wrote to the United Nations envoy to Sudan welcoming the ceasefire agreement but complaining of severe human rights abuses against civilians that they said took place as the fighting raged and should be investigated.
Neighborhood committees that have been at the forefront of local aid efforts in the capital were preparing to receive supplies, though much of the aid that has arrived in Port Sudan on the Red Sea coast is yet to be distributed as agencies wait for security clearance, activists and aid workers said.
The ceasefire deal has raised hopes of a pause in a war that has driven nearly 1.1 million people from their homes, including more than 250,000 who have fled to neighboring countries.
"Our only hope is that the truce succeeds, so that we can return to our normal life, feel safe, and go back to work again," said Khartoum resident Atef Salah El-Din, 42.
Although fighting has continued through previous ceasefires, this was the first to be formally agreed following negotiations.
The ceasefire deal includes for the first time a monitoring mechanism involving the army and RSF as well as representatives from Saudi Arabia and the United States, which brokered the agreement after talks in Jeddah.
US Secretary of State Antony Blinken said the monitoring mechanism would be "remote", without giving details.
"If the ceasefire is violated, we'll know, and we will hold violators accountable through our sanctions and other tools at our disposal," he said in a video message.
"The Jeddah talks have had a narrow focus. Ending violence and bringing assistance to the Sudanese people. A permanent resolution of this conflict will require much more," he added.
Shortly before the ceasefire was due to take effect, the RSF released an audio message from its commander Mohamed Hamdan Dagalo, known as Hemedti, in which he thanked Saudi Arabia and the US but urged his men on to victory.
"We will not retreat until we end this coup," he said.
Both sides accused each other of an attempted power grab at the start of the conflict on April 15.
The United Nations envoy to Sudan warned on Monday of the increasing "ethnicization" of the military conflict.
"The growing ethnicization of the conflict risks to expand and prolong it, with implications for the region," Volker Perthes told a briefing at the UN Security Council.
Sudanese activists have written a letter to Perthes complaining of indiscriminate shelling and airstrikes against residential areas as well as the taking of civilians as human shields, extrajudicial killings, torture and sexual violence.
The crisis is putting pressure on Sudan's neighbors.
Sudanese refugees are streaming into Chad so quickly that it will be impossible to relocate them all to safer places before the start of the rainy season in late June, a senior Red Cross official said on Tuesday, flagging the risk of a disaster.
Some 60,000-90,000 people have fled into neighboring Chad, the UN refugee agency said this week.