Kenya police say three suspected extremists were killed by border police whose vehicle was blown up by an improvised bomb.
A senior police official detailed the attack to The Associated Press but insisted on anonymity because he was not authorized to speak with media.
He said the Monday evening explosion injured two officers in the southern Kiunga area near the Somali border, and the explosives are believed to have been planted by al-Shabab extremists from Somalia who were targeting security units.
He also said the militants hid in the bushes around the area where the bomb went off and then ambushed the Toyota Land Cruiser.
Al-Shabab has vowed retribution on Kenya for fighting the militants who are attempting to topple Somalia's weak U.N.-backed government.