Three police officers were killed and one was wounded in an attack apparently staged by FARC rebels over the weekend on a patrol in Segovia, a town in northwestern Colombia, the National Police said.
Initial reports from officials had blamed the smaller National Liberation Army, or ELN, guerrilla group for the attack.
Antioquia province Government Secretary Santiago Londoño had told reporters that four officers had died in the attack and two were missing, but the figures were later updated.
The police patrol "was ambushed, presumably by members of the 4th Front of the FARC (Revolutionary Armed Forces of Colombia)," the National Police said in a statement.
Antioquia police commander Col. Gerardo Acevedo initially told the press that the ELN, which operates in the area, carried out the attack.
The officers took fire from rebels who had taken up positions on a mountain, the National Police said.
National Police units, with air support from the air force, launched an operation with army troops to locate the rebels.
Five members of a medical team, meanwhile, were wounded Sunday in a new attack staged by the FARC on Toribio, a town in the southwestern province of Cauca, municipal officials said.
FARC guerrillas attacked police and army units with explosives, and one bomb fell on the town's clinic, Toribio Mayor Esequiel Vitonas told Efe by telephone.
"Five people from the medical team are wounded," Vitonas said, adding that the "a chief nurse" was the most seriously wounded person.
Soldiers engaged FARC rebels Saturday morning in Toribio, the army said, adding that at least 50 dwellings were damaged in the attacks.
The FARC attacked Toribio 10 times during the first six months of this year, the mayor said.
Four people were killed in the town last year when the FARC detonated a truck packed with explosives.
The bombing destroyed 20 houses and damaged 170 others in the town, Vitonas said.
Toribio, Jambalo, Miranda and other towns in Cauca are frequently attacked by the FARC.
President Juan Manuel Santos ordered the deployment on June 13 of three additional army brigades and four battalions to root out National Liberation Army, or ELN, and FARC guerrillas.
The soldiers were deployed in Arauca and Norte de Santander provinces, which are on the border with Venezuela, as well as in Cauca and Nariño provinces.
The Colombian government has made fighting the FARC a top priority and has obtained billions in U.S. aid for counterinsurgency operations.
The FARC, Colombia's oldest and largest leftist guerrilla group, is on both the U.S. and EU lists of terrorist groups. Drug trafficking, extortion and kidnapping-for-ransom are the FARC's main means of financing its operations.
The FARC has suffered a series of setbacks in recent years at the hands of the Colombian security forces.
Alfonso Cano, the FARC's top leader, was killed on Nov. 4 in a military and police operation that the government hailed as the biggest blow to the FARC in its nearly 50-year history.
Cano, a 63-year-old intellectual who had entered the ranks of the FARC 30 years ago, was killed in in a remote area of the southwestern province of Cauca a few hours after fleeing a bombardment.
The FARC also suffered a series of blows in 2008, with the biggest coming in July of that year, when the Colombian army rescued a group of high-profile rebel-held captives: former presidential candidate Ingrid Betancourt, U.S. military contractors Thomas Howes, Keith Stansell and Marc Gonsalves, and 11 other Colombian police officers and soldiers. EFE