Police in Kenya's capital, Nairobi, have shot 12 Mungiki suspects during a major crackdown on followers of the banned sect, a commander says.
Police forced local people to lie on the ground as they made arrests
The police and paramilitaries have sealed off Mathare slum for a third day in a search for guns and sect members.
The BBC's Karen Allen at the scene says she saw several dead bodies being brought out of slum dwellings.
Twenty-one people were killed by police in a shoot-out on Tuesday following the killing of two policemen on patrol.
"When we were arresting, some of them came out shooting. As we fired back, 12 were killed," police commander Paul Ruto told AP news agency.
The police operation comes a day after Security Minister John Michuki vowed to intensify operations against the sect.
Our reporter says she also saw about 40 people - including women and children - being forced by police to lie down in the mud as the operation continues.
Many residents have fled the Mathare slum, which is home to some 500,000 people and believed to be a Mungiki stronghold.
KENYA'S SECRETIVE MUNGIKI
Banned in 2002
Thought to be ethnic Kikuyu militants
Mungiki means multitude in Kikuyu
Inspired by the Mau Mau rebellion of the 1950s
Claim to have more than 1m followers
Promote female circumcision and oath-taking
Believed to be linked to high-profile politicians
Control public transport routes, demanding levies
Blamed for revenge murders in the central region
A reporter for Reuters news agency said he saw an officer club a woman in the throat as she clutched a baby.
Earlier, Mungiki members threatened to behead more people.
Albert Kimanthi, the police chief in Muranga district north of Nairobi, confirmed that threatening leaflets authored by the sect members were circulating in the area.
The Mungiki warn that unless residents and traders pay protection fees, they will behead 20 people.
The sect is accused of beheading more than a dozen people in the capital and parts of the central province, in the past three months.
"We assure the residents that we have beefed up security in the area and will counter the sect effectively," Mr Kimanthi told reporters in Muranga.
The leaflets ask transport operators, small businesses and homesteads to pay between $1 and $3 as a daily protection fee.
Mr Michuki, who chaired a meeting with leaders from the most affected areas, said they all support a merciless campaign against the Mungiki.
A beheaded corpse was discovered in Mathere on Wednesday
Last week, the president warned that Mungiki activities would no longer be tolerated and ordered a shoot-to-kill policy.
The Mungiki are thought to be militants from Kenya's biggest ethnic group, the Kikuyu.
Some commentators have linked them to politicians wanting to cause unrest and fear ahead of December elections.
The sect promotes female circumcision and oath-taking and was outlawed in 2002.