Kenyan police say gunmen attacked two churches in the eastern town of Garissa Sunday, killing 17 and wounding at least 40.

Authorities say the attackers threw grenades and opened fire on worshippers.

The deadliest attack took place at the African Inland Church, where at least 10 people were killed, including two police officers. The second attack took place at a Catholic church.

There was no immediate claim of responsibility. Police have blamed previous attacks on sympathizers of the Somalia-based Islamic militant group al-Shabab. Kenya sent troops into Somalia last year to help hunt down al-Shabab militants. The insurgents want to turn Somalia into a strictly Islamic state.

The White House strongly condemned Sunday's attacks and extended deepest condolences to the families of the victims. It said the perpetrators show no respect for human life and dignity and must be brought to justice.

Garissa is about 140 kilometers west of the Somali border. It is also about 80 kilometers southwest of the sprawling Dadaab refugee camp, which houses nearly 500,000 Somali refugees.

Friday, several gunmen at the Dadaab camp killed one Kenyan and kidnapped four foreign aid workers.