Gunfire and an explosion have been heard near the army headquarters and the French embassy in the capital of Burkina Faso, Ouagadougou.
Witnesses have reported seeing armed men getting out of a car and opening fire before heading towards the embassy.
"An attack is under way," the French ambassador tweeted.
Pictures from the scene show a cloud of black smoke rising into the sky. It is unclear who is behind the violence.
The national police have issued a statement saying special forces are in action.
Ouagadougou Mayor Armand Béouindé told France's Le Monde newspaper that the attackers shot at the town hall and his office windows were shattered. "Apparently, it is a jihadist attack," he said, but gave no further details.
French President Emmanuel Macron was being kept up-to-date, said the Elysée Palace in Paris. He has urged French nationals in the country to follow the embassy's advice and stay away from troubled areas.
French forces based in the country have also been deployed.
A statement on the French embassy's Facebook page said it was not clear which locations were being targeted.
It appears to be a twin assault as the city's military barracks and the embassy - which is also near the prime minister's office - are about one kilometre (half a mile) apart.