Sudanese security forces reportedly used violence to break a sit-in outside the Defence Ministry in central Khartoum on Monday.
The Transitional Military Council (TMC) assumed power in April after the military ousted President Omar al-Bashir after three decades in power.
The military council is allegedly not opposed to protesters forming a government if it maintains overall authority during the interim period.
But demonstrators want civilians to rule during the transitional period and lead the African country towards democracy.
The TMC has vowed in the past to not use violence against protesters camping outside the Defence Ministry. They have not issued a statement about Monday's violence.
Arab television stations showed protesters running away from the camp as black smoke rose from tents allegedly set alight by the security forces.
There were also reports of gunfire at the raid and eyewitnesses say there are fatalities.
Britain's ambassador to Sudan said he was "extremely concerned" about the gunfire heard from his residence.
The US embassy in Sudan said the attacks were "wrong and must stop".
Sudanese security forces' attacks against protesters and other civilians is wrong and must stop. Responsibility falls on the TMC.
— US Embassy Khartoum (@USEmbassyKRT) 3 июня 2019 г.
A leader of Sudan's protest movement classified the raid by security forces as a "coup" against the uprising that led to the ouster of al-Bashir.
"We will confront it by escalating protests, marches and full civil disobedience," said Khalid Omar Yousef, a leader of the Declaration of Freedom and Change Forces.
Extremely concerned by the heavy gunfire I've been hearing over the last hour from my Residence and reports that Sudanese security forces are attacking the protest sit-in site resulting in casualties. No excuse for any such attack.
— Irfan Siddiq (@FCOIrfan) 3 июня 2019 г.
This. Must. Stop. Now.