Nairobi -- Kenyan police investigating the slaughter of 21 people this week in Nairobi said on Wednesday they had arrested a leader of a shadowy sect blamed for the killings and an opposition politician.
Ibrahim Ndura Waruinge, a leader of the unregistered Mungiki sect, and opposition member of parliament David Mwenje had been detained along with 29 others in connection with the violence on Sunday and Monday in the slum district of Kariobangi North slum, Nairobi police chief Geoffrey Muathe said.
It was the Kenyan capital's worst bloodshed in years and some commentators have associated it with tensions between two of the country's biggest tribes that could prove particularly troubling ahead of a general election in December.
"Last night we were able to pick (up) the national co-ordinator of the Mungiki...He will be interrogated," Muathe told reporters.
He did not elaborate on the reason for Mwenje's arrest, saying only he was helping police with inquiries. The politician belongs to the opposition Democratic Party. It is supported mainly by Kikuyus, Kenya's largest tribe, which also provides much of the membership of the Mungiki sect.
Residents said members of Mungiki rampaged through the slum, hacking at passers-by, in retaliation for the death of two of their own killed by a gang calling itself the "Taliban." At least one person was beheaded and the sexual organs of some of the others were mutilated.
The majority of the dead and the 31 injured were from the Luo community, another of Kenya's largest tribes, Muathe said.
Some residents said the Luo were targeted because the leader of the "Taliban," a gang of young men providing private security in the mud-walled slum, comes from the community.
Kikuyu and Luo politicians spearheaded the country's struggle for independence from Britain in 1963 but later parted ways amid cultural and political differences.
The government has come under sharp criticism from the opposition for lax security in Nairobi that they say allows armed groups to thrive.
Leaders say such violence coming ahead of general elections in December could lead to tribal clashes.
Lately, Mungiki, whose leaders converted to Islam last year, has attracted enemies for violently forcing people to follow its beliefs. Waruinge has three other cases pending in court associated with violence.
The members normally have long dreadlocked hair -- associated with the Mau Mau movement which fought for independence from Britain in 1950s -- but police have insisted it is difficult to identify and arrest them.
"Mungiki looks like an illegal political movement. It is not registered anywhere, it is not recognised," Muathe said.