The gunmen forced the hostages into a boat and took them deep into the jungle
The Colombian government has accused the country’s second-largest rebel group, the National Liberation Army (ELN), of kidnapping eight people in an isolated region.
The gunmen forced the hostages into a boat and took them deep into the jungle in the western Chocó department, the army said.
A huge rescue operation is underway.
Peace negotiations with the ELN started in February and another round of talks is due to begin in Ecuador next week.
The government demands that the rebels stop kidnapping people, as they frequently do for financial gain.
Details are still unclear about Sunday’s incident, which happened in a rural area of the town of Nóvita, 540km (335 miles) west of the capital, Bogotá.
The hostages were seven men and a woman, all of them youngsters, local media report.
Colombia’s Defence Minister, Luis Carlos Villegas, said 500 soldiers would be deployed to the region, in addition to the 6,300 men already in the area, a statement said (in Spanish).
The country’s chief negotiator, Juan Camilo Restrepo, said on Twitter that the kidnapping “hamper enormously” the negotiations with the ELN.
The talks with the group follow a peace agreement between the government and Colombia’s largest rebel group, the Farc, last year.
The ELN rebels
The guerrilla group was founded in 1964 with the stated aim of fighting Colombia’s unequal distribution of land and riches, inspired by the Cuban revolution of 1959
Over the decades, the group has attacked large landholders and multinational companies, and repeatedly blown up oil pipelines
To finance itself it has resorted to extortion, kidnappings and drug trafficking
It has been strongest in rural areas
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