Police in Homa Bay are looking for three suspects who were captured on CCTV camera attacking and killing a petrol station attendant in Olare trading centre on Sunday.
The gangsters, who masqueraded as customers, are seen hitting the attendant with a metal rod before he collapses and dies.
Homa Bay Directorate of Criminal Investigations Officer Abed Kavoo said the thugs disappeared on a motorbike.
The chilling video circulating on social media shows one of the criminals drawing a metal rod from his coat and attacking the attendant, who collapsed after being hit on the head.
The thug then hits him again as he lies on the ground.
Posed as customers
The thugs arrived on a motorbike and pretended that they wanted to buy petrol.
The attendant began serving them.
But as he fuelled the motorcycle, one of the thugs hit him, sending him straight to the ground.
He was then robbed of the money he had in his pockets.
The assailants then proceeded to assault a security guard who tried to intervene.
The guard suffered serious injuries and was rushed to Homa Bay County Referral Hospital.
Mr Kavoo said the killing was being investigated.