A dormitory at St Pius X Seminary, Nkubu in Meru County was Thursday evening burnt down.
Property worth millions of shillings was destroyed.
Two students were arrested on suspicion of planning and burning the dormitory and were taken to Nkubu Police Station for interrogation.
The dormitory housed 120 students.
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The school's director, Fr Lawrence Micheni, said the two were arrested by their fellow students who suspected they were involved.
"The boys were leaving a church service to the dining hall for their supper when the incident occurred," said Fr Micheni.
The director added that the affected students would be housed in other dormitories before they make a decision Friday.
No casualties were reported during the 7pm incident.
The students and workers managed to salvage a few belongings.