Jamhuri High School was closed on Wednesday after students fought over allegations of religious discrimination.
It will remain closed until Monday to give room for investigations into what caused unrest, during which tens of students were injured.
Some of them were stabbed during the chaos that started on Tuesday when a Muslim and a Christian reportedly differed in the dining hall.
The matter was reported to principal Fred Awuor who calmed the students but trouble started again today.
Awuor said: “Small issues always come up in schools. We are investigating the issue … there is no school that lacks small issues.”
Lonah Mumelo, chairperson of the board of the Nairobi school, said the reports from investigations will be evaluated and given to relevant authorities.
“We have to asses the situation. If it is what the school can manage, we will do so. All these things are under investigation.”
She said the injured were treated and taken home by their parents.