Gunmen fatally shot two French soldiers in Central African Republic’s volatile capital, officials said Tuesday, underscoring the enormous challenges of a new French military intervention in its former colony that includes disarming thousands of rebels accused of attacking civilians.

President Michel Djotodia condemned the attack on the French forces and blamed former leader Francois Bozize, whom he ousted from power in March, for creating the turmoil now being unleashed on the streets of Bangui. More than 500 people have been killed in the capital since Thursday and some 100,000 forced from their homes, aid officials say.

The deaths of the French soldiers came as French President Francois Hollande paid a visit to Central African Republic on Tuesday night, heading into the tumultuous capital after attending a memorial in South Africa for Nelson Mandela.

The early French casualties underscore the volatility of the mission to disarm combatants and bring stability to a largely anarchic capital.

Tensions flared again Tuesday as a mob of young men set fire to a mosque in the Fou neighborhood of Bangui. Smoke billowed from smoldering vehicles nearby, and young men used pick axes and whatever tools they found to try to tear down the walls of the mosque.

Elsewhere, citizens killed three suspected ex-rebels in the Miskine neighborhood of Bangui after the men apparently fired weapons at civilians, residents said.