More than 500 pupils of Toi Primary School demonstrated against a 31-year-old teacher accused of sexual assault.
The teacher was popular with pupils since he was reportedly talented and likeable, source said.
His misdeeds were exposed after a pupil confessed he had sodomised him on many occasions.
At the weekend, pupils and parents at the school learnt that the tutor has been preying on poor and naïve pupils, a majority of whom live in Kibera slum.
Hassan Ibrahim, a parent at the school, said a Standard Four pupil on Saturday reported that the teacher had repeatedly molested him.
“The boy has been quiet about it all along. It is only that this time round the teacher hurt him badly. Blood and a watery substance were oozing from his (victim's) anal region. He was unable to walk properly or go for a long call,” Ibrahim told The Standard.
Parents said the incident occurred on Saturday.
“On Saturdays, the pupils learn until lunch hour and then leave for home. The sodomy occurred after the other pupils had left for home,” another parent said.
According to Ibrahim, after the parents of the assaulted boy noticed the injuries, they took him to the Nairobi Women’s Hospital.
“The doctor confirmed that the injuries were as a result of rape, and that it had been going on for a long time,” he said.
It was during the probe by the doctor that the 11-year-old pupil revealed that he had been sodomised by the teacher.
“So far, three more boys and one girl have come forward, but we suspect there could be more victims,” said Kate Wangui, a rights activist who is one of those mounting pressure on the police and education officials to take action against the culprit.
One of the sexually assaulted boys is disabled.
Victims recounted how the 31-year-old teacher, whom parents said had taught at the school for between three and four years, coerced and molested them.
Parents said the victims' ages range between 10 and 12.
According to the parents and activists, the victims revealed that the teacher sexually assaulted them inside locked classrooms and at his house.
On Monday, Teachers Service Commission officials were at the school questioning pupils and teachers, as investigations into the sexual assault claims began.
The suspect is detained at Kilimani Police Station.