The Sunday killings were the second this week in the central Sulawesi province – the scene of horrific communal violence in 2000 and 2001 which left up to 1000 people dead.
A police officer speaking on condition of anonymity confirmed the killings. He said all the dead were Christians. The attackers were believed to have fled "into the mountains," he said, giving no more details.
Witnesses said at least 12 other people were wounded, but there were no further details about the extent of their injuries.
"There was no damage to houses or churches in the villages," deputy Poso police chief Tranggono told Reuters, adding that the identity of the attackers was not known.
Like the neighbouring Maluku islands, Sulawesi was ravaged by violence during the 1999-2001 presidency of Abdurrahman Wahid. His successor, Megawati Sukarnoputri, has brought relative calm to the region.