Suspected Islamist militants killed 25 people including 13 soldiers in multiple attacks in central Mali, burning down an army base and ambushing troops sent as reinforcements, the army and local authorities said on Tuesday.

The attacks were the deadliest since the Aug. 18 military coup that overthrew President Ibrahim Boubacar Keita, and came just days after scores of jailed militants were freed by the interim government in a prisoner swap.

Nine soldiers were killed in the first attack that took place overnight against a base in Sokoura near the border with Burkina Faso, an army statement said.

At around 8:30 a.m. (0830 GMT) on Tuesday, another three soldiers were killed in an ambush at a bridge near the base as their unit headed to the scene of the first attack, it said.

Nine militants were killed in clashes with the reinforcement unit and two of their vehicles destroyed by the air force.

In a third assault about 40 minutes later near the town of Bandiagara, gunmen ambushed a commercial truck, killing 12 traders and one soldier, according to Moulaye Guindo, the mayor of nearby Bankass, to which the traders were en route.

A witness said he saw nine bodies at the military base and helped transport 20 wounded to local medical centres.

“They (jihadists) took all the vehicles and burned those they could not take away. The camp is burned,” said the witness, who asked not to be identified for fear of reprisal.

A transitional government has been appointed since the military coup. But regional and international powers fear the violence could further destabilise the West African nation and undermine a French-directed military campaign against insurgents linked to al Qaeda and Islamic State in the wider Sahel region.