WAJIR, Kenya (AP) — Two people were killed in a suspected al-Shabab attack at a church in an eastern Kenyan town, a police official said Sunday.

Kenyan police chief Leo Nyongesa said that a woman and her two grandchildren were also injured when attackers hurled a grenade at the Pentecostal Church in Garissa late Saturday.

Ibrahim Makunyi, the head pastor at the church, said the house near the entrance of the church that belonged to a church elder had been bombed.

"One of the dead is a member of the choir, and the other is the son of the church elder," he said.

Witness Mary Nginya said that after the explosion she heard attackers say "It is just the beginning," in Swahili.

Another bomb was thrown Saturday at a busy taxi circle frequented by military officers, but it failed to explode, Nyongesa said.

Police have opened an investigation, but no arrests have been made, he said Sunday. Police are not ruling out that it could have been an attack by the al-Qaida-linked Islamist militant group al-Shabab, he said.

Al-Shabab have promised retaliatory attacks to protest Kenya’s military operation in Somalia.

The bombings came hours after a blast went off along a road in the world’s largest refugee camp in eastern Kenya near the border with Somalia. No one was injured in what appeared to be a minor explosion, officials said.