Panic gripped motorists along the busy Thika Superhighway in the Pangani area after suspected armed goons blocked the road following an earlier demolition exercise, triggering a major traffic snarl-up and leaving hundreds of commuters stranded.
The group reportedly claimed they were protesting the demolition of their structures by authorities.
Long queues of private and public service vehicles stretched along the highway as traffic ground to a standstill, forcing many motorists to wait until the situation was brought under control before continuing with their journeys.
Witnesses said some of the suspected protesters were armed with machetes and other crude weapons as they moved along the highway.
During the chaos, some motorists were allegedly robbed, although the extent of the incidents was not immediately established.
Armed police officers were deployed to the scene and moved in to restore order. It was not immediately clear whether anyone was injured during the confrontation.

The incident has renewed concerns over the infiltration of protests by organised criminal gangs, with motorists increasingly becoming targets of intimidation, vandalism and theft during such disruptions.
The latest developments come barely two weeks after President William Ruto directed Interior Cabinet Secretary Kipchumba Murkomen to launch a nationwide crackdown on goons and those suspected of financing them.
Speaking on June 19, the President accused some politicians, particularly from the opposition, of sponsoring organised youth gangs to orchestrate violence, attack political opponents and cause public disorder.
There has been a growth in use of armed goons by politicians to meet their demands.
Police say they are usually told not to touch the goons.
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