Three guards were killed on Friday night by at a garage they were guarding in Suneka Town, Kisii County.
The gangsters made away with several motor vehicle spare parts and dozens of computers in the midnight raid.
Acting Chief John Nyangenya said they were tied up and killed.
"They [gangsters] tied them up, bundling them into one of the cars parked at the garage before killing them one after the other.
“Their bodies lay in a pool of blood. They died a cruel death," Mr Nyangenya told journalists at the scene on Saturday.
He said the heavy rains that pounded the area throughout the night made it difficult for neighbours to respond to their distress calls.
Kisii County Police Commander Abdi Hassan said police have are investigating the incident.
"Officers have visited the scene to start investigations. Meanwhile we appeal to residents to volunteer any information that can lead to the arrest of any suspect involved in the killing," he said.
The bodies were taken to Nyangena Mortuary.
Separately, a shamba boy was burnt to death in Borabu, Nyamira County, after the house he was sleeping in was torched on Thursday night by unknown people.
The home owner, Ms Liner Manyara, who was sleeping in another house, survived but was injured on the head following the raid.
Police in the area are investigating.
The shamba boy's body was taken to Nyansiongo Mortuary.