Two children are fighting for their lives at Olenguruone sub-county hospital in Kuresoi South after their mother poisoned them.
The woman also took the same poison in an attempted suicide, but was rescued and taken to hospital.
The woman is said to have given the children, a boy and girl, Triatix, an acaricide used to control ticks.
Neighbours said the children were foaming at the mouth, but their 26-year-old mother was reluctant to take them to hospital.
The mother also started foaming at the mouth and that is when some neighbours stepped in.
"I was shocked to find neighbours forcing her into a car. I also noticed the children were weak. I was later informed the three had taken poison," said the woman's sister.
She said this was not the first time her sister had attempted suicide by taking poison. "She did the same thing in 2007 but was saved. She tried it again recently and a neighbour saved her."
She added: "We do not know what is troubling her. My sister has not been herself for the past two years. We have tried talking to her but she wouldn't open up. And now she wants to poison the children. It is worrying."
John Kipruto, a nurse at the hospital, said the three were in a critical condition when they arrived.
"We managed to stabilise them but they have been unconscious for hours now,” said Kipruto.
Tinet chief Jonathan Busienei said they had launched investigations to establish why the woman tried to kill herself and her children.