Ten soldiers were killed and 17 injured in western Colombia Wednesday, in a dawn attack on an army garrison that officials blamed on leftist FARC guerrillas.
The attack occurred in a small town in Cauca province, governor Temistocles Ortega told Blu radio, adding that four of the injured soldiers are in serious condition.
The Cauca region has been a stronghold for the rebel fighters, who are in peace talks with the Bogota government to end more than a half-century of hostilities.
"This is precisely the war that we are trying to end," President Juan Manuel Santos said on Twitter.
The FARC in December declared a unilateral ceasefire, which it has said was meant to advance the negotiations, which have been under way since November 2012.
The Colombian government last month temporarily halted air raids against the Marxist rebels.
The five-decade-long conflict has killed more than 200,000 people and uprooted more than five million.