Sudan says it has thwarted an attempted military coup, and arrested “all those involved”.
A government spokesman told state media the coup plotters were linked to the ousted President Omar al-Bashir, who was toppled two years ago.
Earlier reports from the capital Khartoum and nearby Omdurman described intense military activity, and the main bridge across the River Nile was shut.
The road to Khartoum and ports have also been blocked.
The plotters had tried to take over a building housing the state media, AFP news agency reports.
A government involving the military, civilian representatives and protest groups is in place, was established as part of power-sharing agreement after President Bashir was ousted in 2019.
The BBC’s media monitoring service reports that several coup attempts have taken place in Sudan since then.
There has been tension within this Sovereign Council which is supposed to be overseeing a return to civilian rule, and BBC Monitoring adds that some are claiming the security lapses in parts of the country may be an attempt by the military to obstruct the transfer of power back to civilians.
Correspondents say elements within the military are thought to be behind several of days of protests in Port Sudan in the east of the country.
The Sudanese government says the situation in the country is now “under control”.
Video footage shared on Tuesday morning appeared to show armoured vehicles on city streets, but AFP news agency reports that traffic now appears to be flowing smoothly in central Khartoum.
According to Reuters news agency, military spokesman Mohamed Al Faki Suleiman says the interrogation of suspects will soon begin.
Journalist Mohanad Hashim in Khartoum says the government is blaming a group of officers disgruntled by Sudan’s tough economic situation.
The BBC’s Africa correspondent Catherine Byaruhanga says Sudan’s transitional government is under pressure to deliver economic and political reforms amid competing demands from conservative and liberal constituencies.