Kijabe Boys High School has been closed after students opposed to mock exams set a dormitory ablaze on Tuesday night.
A worker, who did not want to be named, said form four students disagreed over whether or not to sit the exams.
“The students went on strike silent as the night but started exchanging words increasingly loudly,” he said.
Lari OCPD Alfred Makoma said property belonging to 44 students was destroyed in the fire.
No one was injured in the blaze that was extinguished by school workers and some students.
Area educational officer Stephen Kitungu said the school is closed until next week for investigations into the cause of unrest.
“Students cannot riot because of exams only.”
Last weekend a dorm at Stephjoy Girls High School in Kikuyu was set ablaze and students at Gatamaiyu Boys High School vandalised buildings.