Masked assailants launched simultaneous gun and grenade raids on two churches in a Kenyan town, killing at least 17 people in the worst attack in the country since Kenya sent troops into Somalia to crush al Shabaab militants.

Attackers wearing balaclavas killed two armed police before bursting inside to target worshippers as they held prayer services. Witnesses say that bodies lay scattered on the floor inside the blood spattered buildings. "It is a terrible scene, you can see bodies lying in the churches," said regional police chief Leo Nyongesa. At least 40 people were rushed to hospitals with several in critical condition, according to the Kenyan Red Cross.

The Red Cross, which put the death toll at 17, flew the three most critically injured victims by air ambulance to the capital Nairobi. "It is a horrible sight to see," said Hussein Abdi, a resident of Garissa, some 140 kilometeres (85 miles) from the border with war-torn Somalia. Kenya has suffered a spate of gun, grenade, and bomb attacks since sending troops into southern Somalia last October to target al Shabaab rebels fighting to overthrow the weak UN-backed government in the Horn of Africa state.