Several members of the Awa indigenous community have been killed by Revolutionary Armed Forces of Colombia (FARC) guerrillas in Nariño, a state bordering Ecuador, reports Human Rights Watch.

The death toll is unclear but FARC claimed it executed 8. Other reports suggest 27 may have been killed.

The FARC suspected the Awa of cooperating with the army and ELN, a rival insurgent group. FARC militants killed some Awa — including children with knives. They returned later and abducted more children.

Human Rights Watch condemned the FARC.

“These cruel killings violate the most basic principles of human decency and dignity,” said José Miguel Vivanco, Americas director at Human Rights Watch. “There is no possible excuse or justification for these horrific actions.”

The group says Nariño is suffering a “severe humanitarian crisis” due to the FARC’s activities in the region, including laying of antipersonnel landmines and forced “confinement” of villages. The U.N. Refugee Agency estimates that violence in Colombia has displaced at least one-third of the country’s indigenous people.