The airport and internet have been shut down and state television broadcasts patriotic music.
The dawn raids follow a time of tension between the military and the country's civilian government.
According to sources to Reuters, Prime Minister Abdalla Hamdok has been placed under house arrest.
A number of ministers and people from pro-government political parties and the civil-military council that governs the country are also said to have been arrested.
- Armed men have arrested a number of politicians and government representatives in their homes, confirms a government source for the news agency AFP.
No internet?
"Gathered military forces" are said to be behind the arrests, according to a statement from the Ministry of Information.
At the same time, telephone and internet access is reported to have been restricted for most people in the country.
Khartoum International Airport has been closed and international flights canceled, reports the al-Arabiya television channel.
Soldiers and members of paramilitary groups can be seen on the streets of the capital, who are said to have been ordered out with the task of restricting civilians' freedom of movement.
But at the same time, the SPA, the most prominent group in the democracy movement, has called for street protests when they want to counteract what is described as a military coup in the act.
A number of protesters are seen waving flags and burning tires on the streets of Khartoum.
Several protests
Recently, several protests have shaken the country.
Opponents of the government want the military to take full control of the government, while supporters of the government want a continued development towards democracy and a fully civilian government.
Sudan has been ruled since 2019 - when the hard-line Omar al-Bashir was ousted - by a civil-military council and a civilian government.
Tensions in the transitional government have increased since authorities said they had stopped a coup attempt in September.