Sudanese soldiers wearing Rapid Security Forces uniforms stormed barricades at the site of the demonstrations outside army headquarters on Wednesday, eyewitnesses told CNN.
Gunfire could be heard, they said.
In a Facebook post, the opposition Central Committee of Sudan Doctors said that 14 people were wounded, including eight who had gunshot wounds.
The Transitional Military Council (TMC), which has held power since Bashir’s arrest last month, had no immediate comment. It was unclear who may have been responsible for the death.
The number of demonstrators has swelled at the site of the sit-in over recent days, becoming a point of contention for security forces as the location is just over half a kilometer (around 0.3 miles) from the presidential palace.
The TMC said a military police officer was killed and a “large number” of protesters injured, attributing that shooting to groups seeking to undermine “the goals of the revolution.”
The opposition Central Committee of Sudan Doctors said at least six people were shot dead Monday, though the group did not specify whether all of them were killed in Khartoum or under what circumstances. On its Twitter page, state media outlet SUNA reported that three of those injured in the shooting were members of the armed forces.
Earlier Wednesday, the TMC and the opposition agreed to a transition period of three years at a joint press conference, with a final agreement on the transition expected to be reached within 24 hours.
The first six months of the interim period will be allocated to signing peace agreements and “halting the war across the country,” according SUNA.
The protests first began in late 2018 over the rising costs of living, and escalated into a push for Bashir’s removal from office, with mass rallies and sit-ins outside the presidential compound and army headquarters. Bashir responded with a crackdown that led to scores of civilian deaths.
“The Public Prosecutor’s Office has charged former President Omar al-Bashir and others with incitement and criminal complicity in the killing of demonstrators in recent events,” it said.
Bashir also faces five counts of crimes against humanity and two counts of war crimes at the International Criminal Court in The Hague, in connection with Sudanese military actions in Darfur between 2003 and 2008.
Sudan’s military has previously said that it would prosecute Bashir, but would not extradite him.
CNN’s Kara Fox and Hira Humayun contributed to this report.