A woman has been arrested in Tuthu village in Kangema for allegedly killing her three-year-old son and injuring her mother.
Kangema OCPD Beren Kipkoech said they suspect the woman stoned the toddler to death since he had injuries on his forehead.
Mr Kipkoech said the suspect, 36, will be charged with murder on Tuesday over the Sunday night incident.
"We have information that the suspect is suffering from mental illness but it's the doctors who will determine that," the OCPD told Nation on phone.
The toddler's body has been taken to mortuary in Murang’a town.
Local residents said they heard distress calls from the family only to be pelted with stones by the suspect when they responded.
"We had to run for our safety as the woman kept throwing stones at us but we informed the authorities," Mr Ishmael Muhanzi, a neighbour, said.
Mr Muhanzi, who peeped through the window, said he saw the body of the toddler lying on the floor with her mother sitting on a chair.
Rwathia MCA Peter Mweri condemned the act and urged residents who live kin with mental illnesses to take them to hospitals to avoid similar incidents.