Three police officers killed and two injured by bomb blast in Kenya
Three police officers have been killed and two others injured when their vehicle ran over an improvised bomb near Kenya's eastern border with Somalia.
The police vehicle was moving from Kula Police Post towards the border town of Liboi, an official said.
He said three other officers were unhurt.
The incident came a day after police chief Joseph Boinnet announced al-Shabab extremists were stepping up attacks on Kenya.
Mr Boinnet said al-Shabab is under pressure from African Union troops supporting Somalia's weak government against the group's insurgency.
In the last two weeks, attacks by the group in Garissa and Mandera counties have increased after a lull.
Last week, an improvised bomb killed four people in a vehicle.
Mandera County has been hardest hit in recent years by an al-Shabab campaign to avenge Kenyan troop presence in Somalia since 2011.
Kenya's troops are part of the African Union force in Somalia.
Kenya has managed to stop the frequency of al-Shabab attacks in its capital, Nairobi, and major towns, but human rights groups claim the government uses methods such as extrajudicial killings that can fuel revenge attacks.