Gunmen have stormed a tourist resort in Mali popular with Westerners and six people are reportedly dead, say local police.
The country's security minister earlier said two people were dead after the attack.
"It is a jihadist attack. Malian special forces intervened and about 20 hostages have been released," Salif Traore told AFP.
"Unfortunately for the moment there are two dead, including a Franco-Gabonese."
Government troops battled the gunmen at the luxury resort Le Campement Kangaba, east of the capital Bamako.
"Security forces are in place. Campement Kangaba is blocked off and an operation is under way," a security ministry spokesman told Reuters earlier.
Malian special forces intervened, backed by UN soldiers and troops from a French counter-terrorism force.
Witness Boubacar Sangare was just outside the compound as the attack unfolded.
"Westerners were fleeing the encampment while two plainclothes police exchanged fire with the assailants," he said.
"There were four national police vehicles and French soldiers in armoured vehicles on the scene."
He added that a helicopter was circling overhead.
The European Union training mission in Mali, EUTMMALI, tweeted that it was aware of the attack and was supporting Malian security forces and assessing the situation.
Earlier this month, the US embassy in Bamako had warned of "possible future attacks on Western diplomatic missions, other locations in Bamako that Westerners frequent".
BBC correspondent Alex Duval Smith said many expats and wealthy Malians headed to Kangaba at weekends, to enjoy the pools, cocktail bar, canoeing facilities, and other activities for children.
Mali has been fighting a jihadist insurgency for several years, with Islamist fighters roaming the country's north and centre.
In November 2015, at least 20 people were killed when gunmen took guests and staff hostage at the Radisson Blu hotel in Bamako.
Al-Qaeda's North African arm, Al-Qaeda in the Islamic Maghreb (AQIM), said it was behind that siege.
Mali has been in a state of emergency since the Radisson Blu attack. It was extended for a further six months in April.
The country's security has gradually worsened since 2013, when French forces repelled allied Islamist and Tuareg rebel fighters from parts of the north.
French troops and a 10,000-strong force of UN peacekeepers have been battling to stabilise the former French colony.