Some 20-25 "bandits" from the leftist National Liberation Army (ELN) stormed the facility, which is used to pump water from an aquifer, and made off with the hostages, General Alejandro Navas told reporters.

The ELN has been at war with the Colombian government since 1964, but is smaller and less well-known than the Revolutionary Armed Forces of Colombia (FARC), which is currently engaged in peace talks with Bogota.