One person died and 15 people were wounded when a grenade was thrown into a church in Kenya's capital during Sunday service, an official said.
Nairobi's deputy police chief, Moses Ombati, said the grenade exploded at God's House of Miracles International Church in Nairobi.
The incident is the latest in a string of grenade attacks since Kenya sent troops into Somalia in October last year.
Al-Qaida-linked al-Shabab militants, from neighbouring Somalia, have vowed to carry out a major attack on Kenya for sending troops in.
The attack follows a US Embassy warning that a terror attack on prominent government buildings and hotels in Nairobi could be imminent.
The embassy said the timing of the attack is not known but they believe it to be at a final planning stage.