Kenya attack: 'Security team to carry out major operation'

Kenyan police chief David Mwole Kimaiyo has said there will be a "major security operation" following a bus attack in northern Kenya.

Suspected members of the Somali militant group al-Shabab have killed at least 28 people in the attack, officials say.

The bus was travelling to the capital, Nairobi, when it was stopped in Mandera county, near the Somali border.