(CNN) At least seven people have been killed and six attackers "neutralized" Friday in Burkina Faso after attacks on the national army headquarters and the French Embassy, a government minister said.

It's not yet clear who was behind the violence in the West African nation's capital, Ouagadougou.

France's special envoy to Africa's Sahel region, Jean-Marc Châtaigner, urged people to avoid the city center in a tweet referring to a "terrorist attack."

Rémi Dandjinou, Burkina Faso's minister of communication, told CNN that an explosive device was used in the attack at the General Staff of the Armed Forces. At least five people were killed and two attackers "neutralized" there, he said.

Security personnel take cover as smoke billows Friday from the French Institute in Ouagadougou.

Four attackers were also "neutralized" and two Burkina Faso security members killed at the French Embassy, according to Dandjinou.

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