Three women from the same family were found dead in a house in Njoro, Nakuru County, on Friday morning.
It is believed that the victims died from carbon monoxide inhalation.
The three were identified as a woman in her 40s and her two nieces, who were in their 20s.
Their bodies were found in beds in a room, which had been locked from the inside, after a suspicious neighbour alerted others who broke in.
Police said the women likely inhaled the gas from burning charcoal.
The woman's daughter narrowly escaped death and was taken to Nakuru Level Five Hospital.
A medic in Mau Narok noted that carbon monoxide, a colourless and odourless gas, is very poisonous.
“Many people have died because of inhaling it while sleeping. Even small quantities of the gas can be extremely deadly, particularly when it is released in a small space without proper ventilation,” said a medic at Mau Narok Health centre.
The medic, who did not want to be named as he did not have authority to speak to the media, asked residents to completely put out fires from charcoal, and other substances that emit the gas, before going to bed.
Mau Narok Member of Assembly, Mr Jackson Githua, said the woman was a casual farm worker while her nieces were waitresses at hotels in the centre.
They hailed from Wanyororo in Bahati sub- county.
Their bodies were taken to the county mortuary.