Chaos erupted on Monday in Kawangware after angry youth blocked Cabinet Secretary Fred Matiangis motorcade.
The CS had visited Gatina School in the area to assess the KCPE preparations in the area ahead of the national examinations scheduled to kick-off on Tuesday.
The angry youth blocked the main gate of the school after the CS allegedly failed to address them.
A source who spoke to Pulse Live said the youth were later dispersed by police officers who responded with teargas cannisters after the crowd attempted to stone the CS motorcade.
Journalists covering the Matiangi's visit as well as the KCPE rehearsals were also caught up in the melee and locked up at the school.
Matiangi had moments earlier addressed pupils and teachers at Githurai Primary School where he assured all education officials and the country of adequate security ahead of the national examinations.
Tension remains high in the area Kawangware after deadly clashes between rival youth groups.
The violence started on Thursday evening, hours after voting in the repeat presidential election ended.