A sombre mood engulfed Sasimua sub-location in Kuresoi North constituency on Monday after a trader killed a colleague before taking his own life following a scuffle.
The two, who engaged in buying and selling of farm produce, are said to have quarreled after one accused the other of business impropriety.
The man is said to have killed his colleague with a knife, and later drunk pesticide before falling in a borehole.
"When I went to fetch water from the borehole, I saw a can of pesticide and the borehole was not covered. When I looked in the borehole, I could see a body floating on water," said Sabina Mukami.
Area sub-chief Charles Ominde confirmed the incident, and called on the residents to embrace dialogue in resolving conflicts.
"It is sad that this had to end this way, we have lost two young men to a problem we would have solved through dialogue," Mr Ominde said.
The bodies of the two were taken to Molo District Hospital mortuary.
Police have since launched investigations into the incident.