Armed clashes took place between the Sudanese army and the Rapid Support Forces in the Sports City area, south of the capital Khartoum, before the clashes spread to other areas of the country.
Al Jazeera correspondent said gunfire was heard near the army's general headquarters and the residence of the head of the Transitional Sovereignty Council, Abdel Fattah al-Burhan, in the Sudanese capital Khartoum.
Roads leading to the presidential palace in central Khartoum were blocked by army heavy armoured vehicles, he said.
According to a source at Khartoum airport, air traffic has stopped at Khartoum International Airport.
The correspondent pointed to a state of panic and the mass flight of citizens from central Khartoum following clashes in the center and south of the capital, and said that the city of Meroe in northern Sudan is witnessing clashes.
Rapid Support Forces are closing the King Nimr bridge between Khartoum and Khartoum North and the Shambat bridge between Khartoum North and Omdurman, he said.
Al Jazeera correspondent also reported that the sound of heavy weapons rocking the Sudanese capital Khartoum due to battles between the army and the Rapid Support Forces.
Reuters quoted eyewitnesses as saying that guns and armored vehicles were deployed in the city of Omdurman, noting that gunfire was heard in the city of Bahri in Khartoum in the vicinity of RSF facilities.
Eyewitnesses had earlier reported that fierce clashes were taking place between the two sides over the air force administration south of Khartoum.
The spokesman for the Sudanese Armed Forces said that the Rapid Support Forces are heavily present at the headquarters of state television, while armed clashes between the army and the Rapid Support Forces are taking place on Al-Ghaba Street in Khartoum, as well as areas south of the capital.
The armed forces also said they took control of the RSF camp in Merowe locality, where elements affiliated with the RSF militia fled.