An area chief is among four people who died in Mandera after their vehicle ran over an improvised explosive device on Friday.
Mandera county commissioner Fredrick Shisia said 11 other passengers were injured.
"There was an incident of an IED involving a public service vehicle, a (Toyota) Landcruiser which was carrying about 15 people and ran over an IED. It exploded, killing four instantly and injured 11," he told Reuters by phone.
Among the casualties were two local leaders. "One chief died and another got seriously injured," Shisia said.
"We suspect it is al Shabaab militants, as they are the ones who are behind planting of IEDs in the area."
Last month, at least eight police officers were killed in two roadside bombings in the area, with al Shabaab Islamist militants based in neighbouring Somalia claiming responsibility.
Al Shabaab, fighting to overthrow Somalia's government and impose its own harsh interpretation of sharia law, says it will continue to attack
Kenya
until it withdraws its troops from an African Union peacekeeping mission in Somalia.
