Some 22 suspected Mungiki sect members have been arrested for allegedly plotting a massacre in the sprawling Nairobi Korogocho slums.
Police also seized several machettes, clubs and metal bars on Tuesday night.
Nairobi provincial police chief Stephen Kimenchu yesterday said officers on patrol bumped into the suspects identifying the houses they planned to attack.
"The 21-man gang was led by a woman. Investigations reveal they were planning to commit a massacre," he told a press conference at Nairobi provincial police headquarters.
The suspects will be taken to court today.
The arrests were made two days after two people were killed and others injured in an attack linked to political violence in Mathare slums, also in Nairobi last weekend.
Dozens of people, victims of the Mathare attack, are admitted to Kenyatta National Hospital with deep wounds.
Mr Kimenchu however said none of the 22 was linked to the weekend killings.
Said he: "Most of the victims in hospitals have deep wounds on their heads. It appears implements similar to those seized in Korogocho were used in the Mathare attacks."
Mr Kimenchu said tension was high in Korogocho and Mathare areas, adding; "There is a heavy police presence in the areas to guard against recurrence of violence."