At least four Sudanese protesters and a member of the security forces have died in clashes in the capital, Khartoum.
They were killed in gunfire at a sit-in outside military HQ where demonstrators are demanding full civilian government.
Protesters said soldiers were responsible, but the army blamed it on “unidentified elements”.
Sudan has been governed by a transitional military council since the overthrow of President Omar al-Bashir last month.
Demonstrators have been occupying the square in front of the headquarters since 6 April, five days before the president was toppled by the military.
Initially, talks between the ruling generals and the protest organisers had shown little sign of progress.
However, just before Monday night’s violence, both sides announced they had agreed on the structure of a new administration.
The gunfire on the streets may point to a division within the military and an attempt to destabilise this process, says the BBC’s Alastair Leithead.
Some generals may feel frustrated that the sit-in continues despite major concessions from the military, while demonstrators feel they cannot leave the streets until they get what they want, our reporter adds.