Shots have been heard from the administrative centre of Guinea's capital Conakry and in nearby areas since around 4 a.m. local time on Saturday (0400 GMT), four local residents told Reuters news agency.
A military source, speaking on condition of anonymity, confirmed that gunfire could be heard around the area called Kaloum but declined to provide further detail.
"There was a lot of shooting at night, around 4 a.m. and again this morning we are hearing shots," Aminata Soumah, a Kaloum resident, told Reuters by telephone.
Guinea is governed by military leader Mamady Doumbouya, who took power in a coup in 2021 - one of eight in West and Central Africa in the last three years. Mali, Niger, Burkina Faso, Chad and Gabon are also run by military officers.
The authorities could not immediately be reached for comment on the situation in Conakry.