Islamic extremists have infiltrated and attacked the city of Gao in northern Mali, the mayor and residents said.
It was the third major attack on the town since it was liberated by French forces in January.
The assault indicates the radical Islamists remain entrenched and able to attack despite the thousands of French troops who have liberated most of northern Mali's towns from control by the extremists.
Gao Mayor Sadou Diallo said the Islamic fighters launched their attack inside the Quatrieme Quartier, or Fourth District. He said Malian forces engaged the fighters and they retreated, but a second column of Islamists then attacked from across the Niger River.
The mayor said that by evening the situation appeared to be under control, though residents said they still heard shooting. He said: "There was heavy gunfire. The situation is under control now. The Islamists entered via Quatrieme Quartier, and the army went to meet them and was able to push them back. There is another group that entered via the river, but they too were pushed back. It's under control."
For nearly 10 months, Gao was occupied by the Movement for the Oneness of Jihad in West Africa, or MUJAO, one of three al Qaida-linked groups which invaded northern Mali a year ago.
MUJAO was among the most brutal, amputating the limbs of so many accused thieves that the public place where they meted out their version of justice became known as "Shariah Square".
In January, the city along with much of the rest of northern Mali was liberated by French troops, who used Mirage and Rafalle jets to bombard rebel positions before launching a ground assault.
The euphoria following the city's liberation was short-lived, however. Gao was the first town to be attacked by a suicide bomber on February 8, a style of attack that was previously unknown in Mali and which has now been repeated in several other northern cities. Also in February, the city was twice attacked by extremists, who again crossed the river from villages that have long followed the Wahabi form of Islam, a far stricter interpretation of the religion than is practised in most of Mali.
Extra French troops have been brought in to reinforce the city's defences, but the frequency of the attacks has many worried that extremism has taken root in Gao's soil.