(CNN) A pregnant woman and six children -- including a 1-year-old baby and a 3-year-old -- were tortured, slaughtered and buried in a mass grave in Panama as part of a bizarre, ritualistic killing by a religious cult, authorities have said.

Nine indigenous people have been arrested and will be charged over the grisly attack, which took place in a remote part of the Ngäbe-Buglé region, home to a large community of native Panamanians.

Authorities said the bodies of three boys and three girls -- two 9-year-olds, plus others aged 1, 3, 11 and 17 -- were found in the grave. The 32-year-old mother of five of the children, who was between four and six months pregnant, was also found dead in the grave.

The victims were killed for not repenting for their sins, the region's public prosecutor, Rafael Baloyes, told reporters. He added that the cult had been active for around three months but had not harmed people until this attack -- prompted when one of its members believed they had received a message from God.

Police raided the premises of the obscure cult and rescued a further 15 people whom they believe were next in line for a similar murder, according to a statement from the public prosecutor's office.

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