The incident happened yesterday at Ng'ereng'ere village in Tarime District.
It is claimed that a person yet to be identified arrived at their house at around 10.00 in the morning when the children’s parents had gone to the market in Sirari town.
Witnesses said neighbours and other good citizens rushed to the house after hearing screams for help.
Ng'ereng'ere village chairman Chacha Ghati said neighbours and other people rushed the children at the health centre but one of them later died.
He said according to initial medical examination conducted, the children consumed a large quantity of poison the kind of which experts are yet to identify.
He said he will convene an emergency village meeting to conduct a secret poll with the collaboration of the police to identify the people who were behind the incident.
The father of the child who lost his life Nyankogoti Masaite said his son was in Std 2 at Ng'ereng'ere Primary School while his kin who survived was in elementary school.
According to the parent he has been living well with his neighbours for many years and never expected such a thing to happen.