Here is why.
The 9 pm Thursday night accident occurred at Suswa trading centre, 60 Kilometers from Narok town and seven other cows were seriously injured in the crash.
Demonstrators barricaded the road and hurled stones at motorists.
According to the local Chief Jeff ole Kishau, the bus was heading to Nairobi from Kisii.
He said the bus driver rushed to the nearby Olasit police station where he reported the matter.
There was a traffic snarl up as vehicles from Nairobi stretched to Satellite area., several kilometres away.
"This is not the first time we have lost cattle in a similar accident, we demand to be compensated for the dead animals.," one of the locals said as quoted by the Star.
The ugly scene unfolds in the midst of rising death tolls form road carnage thanks to the reckless driving in the festive season.
Over 200 peopl have died in December 2017 alone thanks to road accidents across the country.