Two people were shot dead and two others were seriously injured at Ndindiruku village in Mwea East sub-county.
The gunmen killed a woman at her business premises on Sunday evening. Her nephew was shot when he responded to her distress call.
Two shop attendants were seriously injured. The attackers fled on a motorcycle.
According to Mercy Wawira, who said she saw the attack, the owner of the business premise, Margaret Wanjiku, 40, died instantly when she was shot at point-blank range.
Ms Wawira, an employee at the premises that comprise a butchery, a bar and a grocery store, said her boss was grabbed by the neck, dragged into the cash office, and ordered to surrender all the money she had.
“A gun-wielding assailant, even after being given the money, shot Wanjiku three times while holding her by the neck. She fell down groaning and died as I watched," she said.
Stephen Macharia, the nephew, was shot as he rushed to Ms Wanjiku's rescue as she screamed for help, according to the witness.
The assailants found the two employees, identified only as Kawira and Kimani, in the butchery's kitchen and sprayed them with bullets.
Most area residents were not aware that the attack, which lasted two hours, was taking place as they were watching World Cup matches.
The village has no police post and the nearest one is at Wanguru town, about 14 kilometers away. The officers arrived at the scene long after the killers had escaped.
The village has an unoccupied police post that was put up in 2010 by the then Mwea MP, Peter Gitau.
The gunmen were suspected to be involved in several criminal activities in Mwea.
An Agrovet truck driver was recently robbed of Sh100, 000 at Mururi market in broad daylight by a three-man gang.
The area police boss, Dorothy Gaitenga, was unavailable to comment on the matter as she was said to be in a meeting for most of yesterday.
