Farc rebels have killed three policemen in Maicao in the north of Colombia, officials say.
Violence has escalated since the end of a unilateral ceasefire by the rebels, which was not reciprocated by the Colombian government.
Bogota claims that 6 Farc members, including senior commander Jacob Arango, were killed in army operations on Thursday.
"It's a strike of great importance," Defense Minister Juan Carlos Pinzon told Reuters news agency.