Three pupils died after lightning struck classrooms at Mkulima Primary School in Kuresoi North Sub-County on Thursday evening.
At least 53 others were admitted to various hospitals in Nakuru County.
The Grade Four and Five learners were in their classrooms when the tragedy occurred at around 3pm.
Headteacher Thomas Sisa said they had just rushed back from their games to seek shelter from heavy rains.
Mkulima Location Chief John Macharia Muhia said he received information about the tragedy from a Nyumba Kumi elder.
“I mobilised residents to rescue the pupils. Doctors are observing 45 pupils who are still recovering from the shock,” Mr Muhia told the Nation.
He urged the government to install lightning arresters in schools to prevent similar cases.
Nakuru Governor Lee Kinyanjui, in his condolence message to families, said the county dispatched three ambulances to transfer critically injured pupils to Nakuru Level Five Hospital.
“The department of health has also dispatched a team of clinical officers and nurses to Kuresoi Health Centre, where 30 are admitted,” he said.
Dr Samuel King'ori said three pupils taken to the level five hospital did not have physical injuries and were stable.
He said they were expecting two more.