NAIROBI, Kenya — The mob struck in broad daylight yesterday, setting fire to the church where hundreds of terrified people had taken refuge. Screams filled the air. Even children were burned alive. Those caught trying to escape the flames — or helping rescue victims inside — were hunted down and hacked with machetes. One man said he had to hide in the filth of a pit latrine to stay alive.

Up to 50 Kikuyus were reported killed in the church in the Rift Valley city of Eldoret in ethnic violence that followed Kenya’s disputed presidential election. The death toll from four days of rioting rose to more than 275, triggering fears of further unrest in what has been one of Africa’s most stable democracies.

The latest bloodshed recalled scenes from the genocide in Rwanda in 1994, when more than a half-million people were killed.

President Kibaki, who was swiftly inaugurated for a second term Sunday after a vote that critics said was rigged, called for a meeting with his political opponents — a significant softening of tone for a man who rarely speaks to the press and who vowed to crack down on rioters.

But the opposition candidate, Raila Odinga, refused, saying he would meet Mr. Kibaki only “if he announces that he was not elected.” Mr. Odinga accused the government of stoking the chaos, telling the Associated Press in an interview that Mr. Kibaki’s administration “is guilty, directly, of genocide.”

The violence — from the shantytowns of Nairobi to resort towns on the sweltering coast — has exposed long-festering tribal resentment. The people killed in Eldoret, about 185 miles northwest of Nairobi, were members of Mr. Kibaki’s Kikuyu tribe.

They had fled to the Assemblies of God Church on Monday night, seeking refuge after mobs torched homes. Video from a helicopter chartered by the Red Cross showed many homes in flames and the horizon obscured by smoke. Groups of people were seen seeking sanctuary at schools and the airport, while others moved into the forest.

Yesterday morning, a mob of about 2,000 arrived at the church, George Karanja, whose family had sought refuge there, said.

“They started burning the church,” Mr. Karanja said, his voice catching with emotion as he described the scene. “The mattresses that people were sleeping on caught fire. There was a stampede, and people fell on one another.” Mr. Karanja, 37, helped pull out at least 10 people, but added, “I could not manage to pull out my sister’s son. He was screaming ‘Uncle, uncle!’ … He died.” The boy was 11.

Up to 50 people were killed in the attack, a Red Cross official said, speaking on condition of anonymity because her name would identify her tribe.