Nairobi (Sunatimes)  A Kenyan police officer has been killed and three others seriously wounded in an explosion in Mandera, a border town along the Kenya-Somali common border.

According to police officials on the ground, an improvised explosion went off near Kenyan police officers patrolling the porous border between the two neighboring countries, killing the officer and wounded the other the officers.

A Kenyan online newspaper, the Eastandard, has reported on its online page, that Kenyan police also revealed that the explosives were mounted on a mobile phone and seemed to have been on a timer it went off as the officers took a rest under a tree.

Police also say they recovered unexploded explosives mounted on a mobile phone.

North Eastern provincial commissioner, James Ole Serien, is quoted by the newspaper as saying that a team is on the ground looking for clues on those behind the incident and that the officers injured during the explosion are been treated in Mandera district hospital.

Some of the local residents in Mandera told Bar-kulan that tension is high in the area, with Kenyan police conducting a major search operation around the scene of the explosion.

They also said gunshots fired by Kenyan police could be heard in some parts of the town.

It is not yet clear who planted the explosions but Kenya police officials at the scene of the explosion pointed it to Al-Shabaab militia in the neighbouring Beled-hawo town on the other side of the border, which they say were ‘testing’ on what the police said they will unveil soon.

The Al-Shabaab led administration in Beled-hawo has not yet released any statement either denying or claiming the responsibility of the explosion in Mandera.