One person was killed and three others were wounded in a grenade blast in the Kenyan town of Wajir, including a man suspected to have hurled the device at a supermarket, police said.
David Kirui, the police commander for the town, which is about 500 km (310 miles) northeast of the capital of Nairobi, said it was too early to say who was behind the Wednesday evening attack.
The region is prone to banditry and low-key clan clashes by pastoralist communities but has also suffered sporadic light arms attacks by the Islamist Somali militia group al Shabaab, which attacked a shopping mall in Nairobi last weekend and killed at least 72 people including foreigners in a four-day siege that captured global headlines.
Kirui said the man who was killed was a casual labourer and sometimes mason in the town dominated by a Somali population and located in an arid area near the border with Ethiopia and Somalia.
Kirui said the suspect suffered "serious injuries" from the shrapnel without elaborating, and he promised to track down five of his accomplices who had escaped under a hail of gunfire from police on patrol and others stationed nearby.