Gunmen killed 16 people and wounded dozens when they opened fire and hurled grenades into two churches in the eastern Kenyan town of Garissa on Sunday, officials said, in the latest in a string of attacks. In apparently coordinated attacks, they burst into churches targeting worshippers as they held Sunday prayer services in Garissa, some 140 kilometres (85 miles) from the border with war-torn Somalia. The attackers later escaped. "At the AIC (Africa Inland Church) 10 people were shot dead within the church compound, and three were injured in a Catholic Church," said deputy regional police chief Philip Ndolo. "We condemn this act in the strongest of terms." Kenyan Red Cross chief Abbas Gullet said others died on the way to hospital, taking the number killed to 16. At least 40 others were wounded, 10 of them critically, he added. Police said up to seven men were involved in the attacks, which come two days after gunmen killed a Kenyan driver and abducted four foreign aid workers from the Dadaab refugee camp, some 80 kilometres (50 miles) northeast of Garissa. "We have not arrested any suspects, but we have reports that five suspects were involved in the AIC attack in a combination of grenade and shooting, while two suspects were involved in the Catholic church attack," said Ndolo. Witnesses said the bodies lay scattered in the blood spattered churches as scores of wounded were rushed to hospital. "It is a horrible sight to see," said Hussein Abdi, a resident of Garissa. "It is a terrible scene, you can see bodies lying in the churches," said regional police chief Leo Nyongesa, adding the attackers had killed two armed policemen who had been posted to guard the churches following previous attacks. It was not clear who was behind the attacks, but Nairobi has blamed similar attacks on members or supporters of Somalia's Al-Qaeda linked Shebab insurgents. Kenya has suffered a spate of grenade attacks, shootings and bomb blasts since sending troops into southern Somalia in October to crush Shebab bases, prompting warnings of revenge attacks by the Islamist fighters. Last week a grenade blast in a bar in Kenya's main port of Mombasa killed three people, a day after the US embassy warned of the threat of attack. The Supreme Council of Kenya Muslims condemned Sunday's church attacks, saying that "all places of worship must be respected." "We want to send our condolences, and we are sad that no arrests have been made yet," said chairman Abdulghafur El-Busaidy. The attacks come as search efforts continued for the abducted aid workers, two men and two women who work with the Norwegian Refugee Council (NRC), and who come from Canada, Norway, Pakistan and the Philippines, according to police. But while Kenya's army scoured border areas for a third day, many fear the gunmen and their hostages crossed swiftly into Somalia, only some 100 kilometres from Dadaab where they were seized from the world's largest refugee camp. Attacks and cross-border raids in the region blamed on the Shebab, including the kidnapping in October of two Spaniards working for Medecins sans Frontieres (Doctors Without Borders), were key to Kenya's decision to invade Somalia. The Shebab still control large parts of southern Somalia, despite recent losses to African Union troops, government forces and Ethiopian soldiers, who have wrested several key bases from the insurgents.