Three children were killed on Tuesday morning after a device they were playing with exploded in Cheptais District.
Area police boss Robinson Mboloi said two of the children were brothers.
The incident, which occurred around 10am at Kapisitet village, caused panic among residents.
The device is suspected to have been abandoned by security personnel involved in Operation Okoa Maisha carried out in 2008 to flush out Sabaot Land Defence Force militia from the area.
Area councillor Nathan Warsama said other explosive devices had been recovered in the area. Residents called for experts to comb the area for explosives.
Mr Mboloi said bomb experts had been called in to determine the type of explosive device it was although preliminary investigations revealed it was a grenade.
Two of the children are said to have been sent to the shop by their mother before the third child joined them.
Mr Jonathan Muaka, a resident, said he heard a loud explosion around 10am as he was looking after his animals.
“I ran to the house for safety immediately. The explosion reminded me of sounds I used to hear years back during Operation Okoa Maisha. This area has been relatively calm for the last two years,” he said.
Mr Leonard Wamalwa, a resident, asked the police to make public the findings of investigations to ease tension in the area.
“We should be told the cause of the explosion to defuse rumours. People will start claiming SLDF and other militia groups caused the explosion,” he said.
Call for calm
Upper Western regional commissioner Rashid Mohammed and area DC Omar Salat toured the scene and asked residents to remain calm as investigations were being done.
At the same time, panic gripped residents of Githura Village in Kieni West District yesterday after the discovery of a bomb near a house.
The explosive believed to have been dropped by colonial soldiers during the Mau Mau war was dug out by workers preparing a construction site only for children to start playing with the strange metal.
According to Mr Joseph Wanyiri, a resident, the device could have been hidden in the heaps of soil transported from the construction site.
“After the soil was levelled my grandchildren picked the metal and started playing with it but one of my sons noticed the piece was strange,” Mr Wanyiri said.
He contacted area chief Lawrence Ngara and his assistant Mathenge Ndung’u who confirmed the metal was indeed a bomb.
Later, CID explosive experts from Nyeri examined the device before carrying it to safety. It was detonated at 3.30pm on Tuesday.
Police urged residents to be cautious since many unexploded devices were lying in the area.