Elsewhere on Sunday, police managed to quell more than two days of fierce fighting around a Catholic monastery that killed 22 people and left 200 homes burned in the Rift Valley, 190 miles northwest of the capital, Nairobi, officials said.
The re-election of President Mwai Kibaki has tapped into a well of resentments that resurfaces regularly at election time in Kenya. But never before has it been so prolonged or taken so many lives.
A government commission says more than 600 people have been killed in violence that erupted after the Dec. 27 election, which opposition leader Raila Odinga accused Kibaki of stealing.
As Kibaki's power becomes more entrenched each day, the opposition's best hope may rest in wrangling a power-sharing agreement that might make Odinga prime minister or vice president. International mediation has so far failed to broker such a deal.
Odinga has called for another "peaceful protest" on Thursday, saying, "let them bring their guns and we will face them." The protest will take place in defiance of a ban and despite the deaths of at least 24 people in three days of protests last week - most of them blamed on police.
Sunday's bloodshed in Nairobi's Mathare slum, like much of the fighting since the vote, was between the Kikuyu and Luo ethnic groups, said resident Boniface Shikami. President Kibaki is a Kikuyu and Odinga is a Luo.
Shikami said Luos in his street had received notices warning them to leave by nightfall or risk attack.
One man staggered past with blood streaming from the stump of his arm, which had been cut off with a machete. The arm was taken by a group of youths and placed on top of a pile of stones barricading an alleyway.
The maimed man, Peter Kyalo, arrived later at Kenyatta Hospital. He said he was warned on Saturday night by Luo friends he might be targeted because he is a Kamba, the same tribe as the vice president, a former presidential candidate who joined Kibaki's government this month.
In a separate incident, around 50 people attacked welder Dominic Owour, a 23-year-old Luo, and tried to cut off both his hands at the forearm, Owour said.
Both men said police watching the attacks did not intervene.
Dr. Njoroge Waithaka said 13 people had been admitted to Kenyatta Hospital from the area around Mathare, mostly with ax and machete cuts on the upper limbs and head. Filipe Rebeiro of aid group Doctors Without Borders said his organization had treated 10 people for machete and ax wounds on Sunday morning alone.
Joshua Omukolong, the area police chief, confirmed at least two people died from overnight fighting.
Resident Moses Ogolla said he saw four bodies loaded into a police vehicle Sunday morning with deep machete cuts.
"I think it was a gang who attacked them because some bodies, the head had six, seven, eight cuts on it," he said. Ogolla said that he believed the victims were Luo because he heard relatives conversing in the Luo language. "The Luo guys say they are going to avenge this."
In the Rift Valley, around the Catholic Kipkelion Monastery, fighting since Friday has pitted Kalenjin people native to the area against Kisii and Kikuyus who settled there in the 1960s and 1970s.
Police appeared to have quelled the violence by early Sunday afternoon but still were recovering bodies.
A local reporter at the scene counted 14 people dead from machete wounds, three bodies stuck with arrows and five people shot dead by police.
The death toll also was confirmed by district administrator Aden Alhake, who said some 200 homes have been burned down in three days of clashes.
Land always has been a tool of Kenyan politicians, who distribute it as favors to their own and allied tribes, and use it as a weapon, settling their supporters in hostile areas in order to win votes at election time.
In the Rift Valley, Kalenjin people who feel they have been wrongly stripped of their land generally support the opposition.
Edward Ndirangu, who said two of his houses were razed, was searching for his wife and three children.
"I am not sure about their safety. ... We fled as they were looting and torched my homes," he said.
He said the Kalenjin were the aggressors. Alhake said 2,500 people taking refuge at three schools and the monastery all were Kikuyu and Kisii.