Islamist gunmen attacked the largest city in northern Mali on Sunday following two straight days of suicide bombings, intensifying their insurgency on territory reclaimed by French-led forces.
In the first large-scale urban guerrilla attack of the conflict, rebels from the Movement for Oneness and Jihad in West Africa (MUJAO) clashed with Malian troops in the streets of central Gao around the main police station and the governor's offices, a Malian security source and AFP correspondents said.
The clashes sent residents running for cover as Kalashnikov bullets and 14.5-millimetre rounds pierced the air. Rocket-propelled grenade explosions, heavy machine gun shots and light weapons fire could still be heard in the city late in the afternoon.
A French Tiger attack helicopter was circulating over the neighbourhood and French and Malian forces were conducting joint patrols, warning residents that snipers could be hidden in the city.
"Many Islamists were killed," said Colonel Mamadou Sanake of the Malian army.
A death toll could not immediately be established, and it was unclear whether any soldiers had been killed.
Sanake said some of the rebels had arrived in the city by motorcycle and others via the Niger river, which passes near the governor's offices.
"MUJAO elements infiltrated the city and we're in the process of rooting them out," the security source said, speaking on condition of anonymity.
Another security source said there were "several dozen" attackers.
A witness said the rebels had hidden in the empty police station, then opened fire on Malian soldiers when they arrived. When reinforcements came, they were attacked by snipers hidden in surrounding buildings.
The man said he had seen one body that appeared to be a civilian hit by a stray bullet.
The latest violence underlined the threat of a drawn-out insurgency as France, whose warplanes continued bombing northern territory Sunday, tries to map an exit strategy nearly one month into its intervention in its former colony.
The clashes came after a suicide bomber blew himself up late Saturday at the same army checkpoint where the first such attack in Mali occurred a day earlier.
His severed head, still lying on the ground the next morning, was later picked up and placed in a wheelbarrow as French troops swept the site at the edge of Gao for landmines, AFP correspondents said.
MUJAO, one of the Al-Qaeda-linked groups that seized control of northern Mali for 10 months in the wake of a military coup in March 2012, claimed the first attack and on Saturday warned of more to come.
"We are dedicating ourselves to carrying out more attacks against France and its allies. We ask the local population to stay far away from military zones and avoid explosions," spokesman Abou Walid Sahraoui said.
The two suicide attackers were the only fatalities in the bombings, although one soldier was lightly wounded in Friday's explosion.
To the northwest, French warplanes bombed a government building in the town of Gourma-Rharous, between Gao and Timbuktu, Sunday morning, targeting military equipment and vehicles that the Islamists had stored there, a local official said.
-- Arab bodies found in Timbuktu --
The north is gripped by tensions between light-skinned Arabs and Tuaregs -- accused of supporting the rebels, whose members were mostly drawn from the two groups -- and their black neighbours.
Residents of a village near Gao on Saturday detained an Arab and a Tuareg they claimed were strapped with explosives.
Friday's suicide attack was carried out by a Tuareg, and Saturday's bomber was either Arab or Tuareg, according to witnesses.
In Timbuktu, a grave containing several bodies, including those of three Arab shopkeepers recently arrested by Malian troops, was discovered Friday, the Mauritanian online news agency ANI reported.
Rights groups have accused the Malian army of summarily executing Tuaregs and Arabs and called on the government to protect them from reprisal attacks.
Mali imploded after last year's coup waged by soldiers who blamed the government for the army's humiliation by a separatist rebellion among the Tuareg, a north African people who have long complained of being marginalised by Bamako.
With the capital in disarray, Al-Qaeda-linked fighters hijacked the Tuareg rebellion and took control of the north, imposing a brutal form of Islamic law.