"A vehicle with four employees of the Kenya National Highway Authority was attacked with an IED, all the four died on the spot," said John Otieno, a local government administrator.
The workers were leading a three-car convoy from the town of Garissa to Bura when they hit an explosive device planted in the road by suspected members of the Somali insurgent group al Shabab, according to a police report.
Spokespersons for al Shabab could not immediately be reached for comment as their phones were switched off.
The Islamist group killed 166 people at Garissa University in 2015, and 67 at a mall in Nairobi in 2013, but the frequency and severity of the group's attacks in Kenya has reduced in recent years.
The al Qaeda franchise's cross-border raids are part of its campaign to pressure Kenya into withdrawing its troops from the African-Union mandated peacekeeping force in Somalia, ATMIS.
