Colombian police say leftist guerrillas killed 16 officers and injured several others in an attack on a police station.
Officials say rebels used homemade mortars in the attack, which also damaged nearby buildings in the northern town of Tierradentro.
Military officials deployed aircraft to help troops restore order following the attack early Wednesday.
Government forces recently returned to the area, after right-wing paramilitaries agreed to hand over control and open peace talks.
Leaders of the rebel Revolutionary Armed Forces of Colombia have rejected calls from President Alvaro Uribe to open talks to end decades of fighting.
Tens of thousands of people have died in the conflict involving rebels, paramilitaries and Colombia's armed forces.
Some information for this report was provided by AP and Reuters.