A special security team has been formed to track down an armed gang targeting motorcyclists in Kerio Valley.
The gun-toting gang, which operates under the cover of darkness, has been laying ambush on cyclists along the Tot-Chesongoch-Arror road.
In the latest attack, one passenger was shot dead while the rider and another passenger sustained serious gun wounds on Friday evening.
This brought the death toll to four in the past two weeks, with a similar number of motorbikes stolen. Several other people are nursing gunshot wounds.
Security officers say the stolen motorcycles are fetch up to Sh100,000 apiece in the neighbouring Baringo County.
Following the attacks, residents have expressed concern that the perennial cattle rustling menace in the region maybe transforming into motorbike theft.
According to area chief Benedict Chebii, bandits have resorted to stealing motorcycles after local herders moved their animals away from Kerio Valley.
The chief warned that pupils in at least 11 schools in the area may not report to schools when learning institutions reopen this week.
Elgeyo Marakwet county commissioner Fredrick Ndambuki said the team comprising different security agencies will launch an operation to arrest and disarm the criminal gangs.
"We have resolved to constitute a security team that will operate stealthily at night to dismantle this emerging form of crime. It has come to our attention the criminals understand the terrain of the area," said the commissioner.
Speaking after chairing a security meeting in Iten over the weekend, Mr Ndambuki banned night travels in the area, saying night movements may jeopardise the operation.
"We are sending a warning to crooks and criminals who seem to have changed their pattern of crime into operating at night that their days are numbered," he said.
He urged security agencies in Baringo and West Pokot counties to help recover stolen motorcycles. Motorcycles form a crucial transport in the area, where the terrain is rough.