GAO, Mali (AP) — Black-robed Islamic extremists, armed with AK-47 automatic rifles, invaded the center of Gao, the most populous city in northern Mali, fighting the Malian army Sunday afternoon.

The Islamic radicals fought against the Malian army for more than two hours and were seen roaming the streets and on rooftops in around the police headquarters in the center of Gao. Heavy gunfire could be heard across the city.

Near the police headquarters, Malian soldiers with rocket propelled grenades traded fire with the combatants believed to be from the Movement for Oneness and Jihad in West Africa, or MUJAO. The only sound was gunfire and the bleating of goats, as residents took cover inside their homes.

Soldiers were positioned at every corner in the neighborhood of mud-walled buildings.

Ever since French forces took the town in January, Islamists had clashed with security forces on the outskirts of Gao, but this was the first time they succeeded in entering the city.

The fighting comes after a suicide bomber detonated himself at a checkpoint at the entrance to Gao late Saturday night. An earlier suicide bomber blew himself up in Gao Friday.

Gao was retaken by French forces two weeks ago. But as the French military moved north to pursue the al-Qaida-linked extremists who had occupied northern Mali, jihadist cells near Gao began planting landmines and carrying out suicide attacks.