NAIROBI, Kenya — Masked gunmen hurled grenades into two churches in eastern Kenya on Sunday and then sprayed gunfire at fleeing worshippers, killing at least 15 people in one of the worst terrorist attacks Kenya has suffered in years.
When Kenyan forces stormed into Somalia eight months ago, the militant Islamist group al-Shabab, Somalia's fiercest, vowed to wreak vengeance, saying it would topple Nairobi's skyscrapers and kill Kenyan civilians.
The skyscrapers are still standing, but militants believed to be connected to al-Shabab have carried out more than a dozen attacks on Kenyan soil, scaring off tourists and putting a serious dent in this country's economy and sense of security.
On Sunday, at 10:30 a.m., four gunmen attacked the African Inland Church in Garissa, an outpost town in the arid flatlands near the border with Somalia. Kenyan police officials said that the gunmen hurled two grenades into the church and shot and killed two police officers who had been posted at the church's door because of several recent attacks in Garissa.
The gunmen then used the police officers' high-powered assault rifles to shoot fleeing worshipers, who poured out of the church in a desperate stampede. Witnesses said at least 15 people were killed and as many as 50 wounded. Scenes of the aftermath in the local media showed bloody bodies sprawled under the church's pews.
At about the same time, two other assailants hurled grenades into a Roman Catholic church in Garissa, wounding three people.
The assailants appeared to have escaped.
The Obama administration condemned the attacks, saying in a statement Sunday that those responsible "must be brought to justice for these heinous acts."
For some time now, U.S. officials have been concerned about a major terrorist attack in Kenya. Last month, the U.S. Embassy sent out a warning to U.S. citizens about an imminent strike in the port city of Mombasa. A day later, a grenade attack at a Mombasa bar killed three people.
Kenya borders Somalia, which has struggled with various degrees of chaos for more than 20 years. Kenyan security forces are widely considered weak and corrupt.