attacks on churches in the Kenyan town of Garissa near Somalia, say the Kenyan Red Cross and a medical official.
Regional deputy police chief Philip Ndolo said balaclava-clad "goons" attacked the town's Catholic church and the African Inland Church (AIC).
A combination of grenades and gunfire was used, police said.
Kenya's border region has been tense since it sent troops into Somalia to pursue al-Shabab Islamic militants.
Kenya said the operations, launched last October, were designed to bring an end to kidnappings on Kenyan soil and other violence which it blamed on al-Shabab.
But since then, al-Shabab has been blamed for a further string of grenade and bomb blasts across Kenya - though it has never admitted to carrying out any such attack on Kenyan territory.
No group has yet said it carried out these latest attacks, but the finger of blame will once again undoubtedly be pointed at al-Shabab or sympathisers.
The Supreme Council of Kenya Muslims also condemned Sunday's church attacks, saying that "all places of worship must be respected". Sunday's attacks took place during morning sermons at the churches in the garrison town.
Police say 10 people died, but the Kenyan Red Cross later said the death toll had risen to 16, a figure confirmed by the provincial medical officer who covers Garissa.
About 40 were thought to be wounded, several in serious condition,Gunmen shot two policemen outside one of the churches, and grenades were then thrown inside. As the panicked congregation rushed to escape, gunmen fired on them, police said. At least 10 people died.
In the second - apparently co-ordinated - attack at a Catholic church, two grenades were thrown inside the church. One failed to go off, but police say three people were injured by the other one.
Police said up to seven gunmen were involved in the attacks, but none had been apprehended.
We will keep you posted as more update unfold.