Heavy gunfire has been heard at a protest outside the Defence Ministry in Sudan’s capital Khartoum and activists said in a statement that security forces were trying to break up the protest by force.
Witnesses also said that Sudanese security forces fired tear gas at thousands of anti-government protesters demonstrating outside the army headquarters.
Witnesses and a protester said on Tuesday that security forces of the powerful National Intelligence and Security Service and riot police were firing tear gas in a bid to disperse the demonstrators from the military complex.
“The security officers are firing heavy tear gas. I can see protesters coughing and covering their faces with hands and medical masks,” a witness told AFP news agency from near the demonstration site.
"I can also hear gunshots but it's unclear who is firing."
Live broadcast by Al-Hadath TV also showed heavy shooting.
Over the past four months, Sudan has witnessed widespread anti-government protests that were sparked by anger over rising bread prices but quickly morphed into broader calls against President Omar al-Bashir's three-decade rule.
The Sudanese armed forces are not "against the demands" of protesters seeking al-Bashir's departure, the country's defence minister has said, warning, however, that the army will not allow a "fall into chaos".
The Sudanese Professionals Association (SPA), one of the groups spearheading the demonstrations, said a soldier was killed on Monday while trying to protect those rallying against Bashir.
Earlier, as crowds in Khartoum shouted slogans such as "Sudan is rising, the army is rising" to encourage the armed forces to back their demands, the protesting Alliance for Freedom and Change group sought direct talks with the army forming a transitional government.
"We reiterate our people's demand that the head of the regime and his government have to immediately step down," Omar el-Digeir, a senior member of the group, said in a statement outside the army headquarters.
"We also call on the Sudanese armed forces to withdraw their support for a regime that has lost its legitimacy," Digei added.
Analysts, meanwhile, said senior military figures were keen to "find a way" for Bashir, whose power base is within the armed forces, to step down "gracefully" and initiate a transition of power.
"The army would like to come out of this as the people who saved Sudan from chaos," said Alex de Waal, an expert on Sudan, told Al Jazeera