Rebels killed two town councilors and a woman in southern Colombia, and apparently sought to kill more.
President Alvaro Uribe has placed police or troops in every municipality across the country, breaking with the past central government practice of abandoning many small hamlets and towns.
But the killings Tuesday night in the town of El Doncello show that local officials remain exposed to violence in Colombia's countryside.
El Doncello councilman Rafael Murillo said that rebels from the Revolutionary Armed Forces of Colombia, or FARC, searched homes for councilors.
Finding two, along with a councilwoman's sister, the attackers killed them.
"This was not only against (those killed), but against all of the councilors," Murillo told The Associated Press. "They just didn't happen to find us at home at that moment."
The office of the United Nation's high commission for human rights issued a statement condemning the killings.
El Doncello is located in Caqueta province, a longtime stronghold of the FARC. In recent months, the FARC has passed around pamphlets demanding the resignation of all local officials.
The vice president of the National Federation of Councilors, Marta Cortez, said the latest attack revealed how vulnerable councilors remain across this country.
"What happened in El Doncello shows the risks we face in the province of Caqueta and in almost all of the rest of the country," she said.
The FARC have carried out similar attacks on local officials, calling them representatives of the national government they have been at war with for more than four decades.
Murillo said the surviving councilors were being protected in a local police station.
According to the National Federation of Councilors, seven councilors have been killed this year. In 2006, 23 were killed across Colombia, six of which were blamed on the FARC.