A police officer shot and killed two forest rangers before he turned the gun onto himself at a camp in Elgeyo Marakwet County.
Police have linked the incident to a love-a-triangle saga.
Constable Evans Kimutai attached to the elite Boarder Patrol Unit, Todonyang, Turkana had traveled to the Cheranganyi Forest Station where he shot and killed the two.
He also shot and injured another ranger at the camp before he took his own life.
Kimutai armed with an AK47 rifle raided the station Sunday midnight and shot dead Abdalla Dzabo Kittole aged 22 and Marion Cherono aged 20, police said.
A third ranger Jeniffer Kilonzi was also shot and injured in the incident.
Kimutai had travelled from Todonyang where he is based to commit the incident after which he shot himself in the chin bursting his head, police said.
A chief for the area Andrew Chemalingo reported the incident to police at Kapcherop who rushed to the scene and found the incident had already happened.
The unit he serves is regarded to have some of the best trained officers.
One AK 47 rifle 17 spent cartridges, three magazines- one which was empty, another with three bullets and another with 30 bullets were recovered at the scene.
The injured woman was taken to hospital while the bodies were moved to the mortuary pending autopsy.
This is the latest such murder-suicide incident to happen in the service amid push for action to address the trend.
It came a day after another cop died by suicide in Migori. The incident happened on Sunday June 2 morning.
It happened in front of his family.
Many say this is linked to their stress.
Dozens of police officers have died as a result of suicide or killed many in a trend that is attributed to stress at work.
As part of efforts to address the trend, police authorities have launched counselling services and the National Police Service Commission has established a unit and staffed it to attend to their demanding situation.
The counselling unit will, among other things, evaluate, design and lead an outreach programme that helps prevent mental health and substance abuse.
At least three suicide cases involving police officers are recorded every month.
Officials say police are generally on the receiving end of all community problems.
They are expected to maintain law and order in very difficult situations, besides putting their lives at risk.
Over the years, a spike in deaths in the service has been linked to trauma.
They include deaths by gun.
