Two French people, one American and one South Korean were freed in the operation. The French military was at first unaware of two of the hostages.
Several hostages, include one American, one South Korean, and two French people were freed in Burkina Faso overnight on Friday by French special forces. French President Emmanuel Macron said that they would be repatriated quickly.
"The precise and determined actions of French soldiers allowed us to take out the kidnappers while protecting the lives of the hostages," France's army chief Francois Lecointre said. He described the militant group as "terrorists" without giving them a precise title. Four kidnappers were killed and two escaped, he said.
Two French service members lost their lives during the night-time operation to release the four from their 28-day ordeal.
"Those who attack France and the French know that we will spare no effort to track them and take them out. We will never abandon our citizens," Armed Forces Minister Florence Parly said on Friday.
The French army had not known about the American and South Korean captives when the operation began: "We were not aware of their presence," Parly said. "The American will be repatriated separately."
At least two of the hostages were captured in neighboring Benin.
"We are grateful for the safe recovery of hostages, including an American, during a recovery operation in Burkina Faso," said Tibor Nagy, the US assistant secretary of state for Africa on Friday.
"I offer my deepest condolences to the families of the French soldiers killed during the operation," Nagy added.