The attack took place Friday about 30 kilometres from Gao, the largest city in the country's northeast where armed groups hostile to the ruling junta operate.
It was the deadliest attack on civilians this year.
The assailants targeted a convoy of some 60 vehicles escorted by the army, military spokesman Colonel Major Souleymane Dembélé told The Associated Press.
He said soldiers assisted the victims and transferred 13 wounded to the Gao hospital.
He said four of the attackers were wounded and declined to comment on any army casualties.
"My sister survived the attack, but she's in a state of mental shock. She saw a lot of dead and wounded, a whole scene of horror. It was the first time she had seen dead people," said a Gao resident, who spoke on condition of anonymity for his own safety.
No armed group has claimed responsibility for the attack.
Several groups operate in the area, including the Islamic State group, the al-Qaeda-linked JNIM, and others from the Azawad region hostile to Mali's military regime.
Mali has been in a crisis for more than 10 years.
The military seized power in 2020, capitalising on the unpopularity of the former democratically elected government, but the new rulers have struggled with deadly militant attacks.
Mali is Africa's third top gold producer after South Africa and Ghana.
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