Masaba South OCPD Martha Ng'etich confirmed the incident saying the dead included two women and a class 8 pupil.
The class 8 pupil was set to sit for her Kenya Certificate of Primary Education (KCPE) at the end of the year.
According to the residents, there were signs of rain in the area but it had not yet started raining when the lightning struck.
Eye witnesses say that the 3 had been burnt beyond recognition.
Relatives, teachers and pupils gathered to stare at the tree where the 3 met their death.
The head teacher of Chironge Primary School John Ogucha termed the incident as “tragic”
The bodies have been taken to Gucha Sub District Hospital in Keroka.