Two night guards were killed and an assortment of construction materials stolen from a site in Kajiado.
The bodies were found long after a gang had raided the site and escaped with materials.
Police said the two were hacked in their heads with blunt objects.
It is suspected they resisted a move by a gang to steal the materials prompting the attack on Tuesday night.
They were guarding a building under construction and therein were materials used at the site.
Police established that 16 pieces of D-8 metal bars, one roll of binding wire, one roll of hoop iron and assorted building materials were stolen from the building that they were found in.
No arrest has been made so far.
Police said the hunt for the attackers has been launched and urged for cooperation from locals.
There is booming construction in the area and demand for such materials is high.
Most contractors have hired guards to take care of their sites. Locals complained the sites are frequently raided and materials stolen by cartels who later sell or use them.
The bodies were moved to the mortuary pending autopsy and further probe.
Rift Valley police boss Tom Odera said they are boosting security in the area to address the locals' concerns.
In Nandi, a man was arrested over the death of his wife.
The woman's body was found lying in her house with multiple injuries.
The man went missing before he was arrested a day later after residents spotted him in Kabujoi.
The motive of the murder is yet to be known but police said investigations are ongoing.
