Kenya is counting its losses after a land-cruiser detonated a bomb planted on a road in the northeast part of the country killing 4 people and injuring 11 others on Friday.

Last month, at least 8 police officers were killed in two roadside bombings in the area, with al Shabaab Islamist militants based in neighbouring Somalia claiming responsibility.

Early on Friday, a public service vehicle was blown up by an improvised explosive device (IED) between Fino and Sheikh Barow, Mandera County Commissioner Frederick Shisia told Reuters.

"A (Toyota) Landcruiser which was carrying about 15 people 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."

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.