Protesters in Mathare, Nairobi, were on Wednesday treated to rare shock after a man who was standing nearby, reportedly turned out to be a police officer.
He was dressed in plain clothes.
In a video seen by the Star, the protesters are heard talking to someone, as one of them asks, "makasiriko unakasirikia nani?"
Someone else is heard warning the others.
"Huyo umesalimia. Haya endeni endeni," he says before the man in question runs towards one of the protesters grabs and holds him.
In the video, the arrested demonstrator was then escorted to a waiting police lorry as some of the officers shouted "Weka juu. Pandisha juu".
The undercover 'protester' was dressed in a blue trouser and a maroon sweatshirt.
The other protesters ran away.
