Five Colombian soldiers were killed by FARC rebels in the first major incident since peace talks between the Andean country's government and guerrilla leaders began earlier this week, the army said on Saturday.
The government and the Revolutionary Armed Forces of Colombia (FARC) started a peace process on Thursday in Norway aimed at finding a negotiated end to the five-decade-old conflict. The negotiations move to Cuba on Nov. 15.
The Friday night attack with explosives by rebels in the southern Putumayo region killed five soldiers and injured 10 more, said army general German Giraldo. The attack took place in a FARC stronghold near the border with Ecuador.
"Our hearts are with the families of the soldiers that lost their lives in this despicable attack with explosives," President Juan Manuel Santos said in his Twitter account.
The peace talks are the latest in a long history of attempts to resolve the war, which has left tens of thousands dead and millions more displaced since the FARC first took up arms against the government in 1964.
Santos is betting that a decade of U.S.-backed blows against the FARC has battered the group to the point it will seriously seek to end the fighting after so many previous peace efforts ended in shambles.
The Colombian government has repeatedly rejected a FARC request that there should be a bilateral ceasefire during the negotiations. The FARC have said they are willing to discuss a ceasefire deal at any point during the peace talks.