Mandera — Kenyan Police have arrested at least 15 Somali men suspected to be behind the soaring spate of grenade attacks in North-Eastern region, witnesses said on Sunday.

The suspects, who are of Somali nationals, were taken into custody for further investigations about yesterday's blast that hit a convoy of pick-ups mounting police forces in Mandera, inuring two soldiers.

A police official, who asked for anonymity because he is not authorized to speak to the press, said Sunday that the suspects were detained in an operation conducted by the army inside Mandere town, North-Eastern Kenya.

Nine of the arrested people are reportedly released after the police didn't find any guilty over the bombing while the rest of six others are still held at a local jail in Mandera.

Kenya sent troops into Somalia last year to try to crush Al Shabaab insurgents it blames for a surge in violence and kidnappings threatening tourism in east Africa's biggest economy.