Eleven soldiers and one policeman died, and another three soldiers were injured in an attack carried out by alleged ELN rebels in the northeast of Colombia on Monday, the military reported.

When attacked, the soldiers reportedly were traveling through the Guican de la Sierra municipality located close to the border between the Boyaca and Arauca provinces after bringing back votes cast by a remote indigenous community.

While the military reported 11 deaths, weekly Semana said that as many as 18 soldiers had died in the post-election rebel ambush.

According to the military, Army commander General Alberto Jose Mejia has taken personal control over efforts to capture or kill the guerrillas responsible for the attack.

The ELN, Colombia’s second largest rebel group, has been fighting the Colombian state since 1964, using the region where the attack took place as one of its main areas of control.

The group’s leadership has been negotiating with the Colombian government about the possible formalization of peace talks, but neither party has ended hostilities.

On Sunday, when the country was holding local and regional elections, the ELN killed another soldier in an attack in the northwest of the country.