The bloodshed, claiming victims on both sides, occurred when Marxist rebels of the Revolutionary Armed Forces of Colombia (FARC) on Thursday morning attacked a camp in the western community of San Jose del Palmar belonging to the right wing United Self-Defence Forces of Colombia (AUC), officials said.
Victor Mosquera, a regional human rights observer, said corpses littered the site of the fighting and that many people were missing. About 100 AUC members were reportedly injured in the fighting.
Government troops have been sent to Choco Province to protect civilians. The paramilitary troops and rebels have for years been fighting for the control of Choco Province because it contains strategically important drug and weapons smuggling routes to the Pacific Coast.
With about 18,000 armed men and women, FARC is Colombia's largest rebel group and has been fighting the state for more than 41 years.
The AUC was founded as a private army by landowners in the 1980s. It later claimed its independence and turned to the drug trade to support itself.
