Kenyan police said they had launched an investigation after the mutilated bodies of six women were found on Friday in piles of garbage at a dumpsite in a Nairobi slum.
Police briefly fired tear gas and rubber bullets to disperse an angry crowd at a police station near the site of the grisly discovery in Mukuru, in the south of the capital, an AFP journalist said.
"The alarm was raised following the discovery of six severely mutilated bodies, all female, in various stages of decomposition," the Directorate of Criminal Investigations said in a statement.
"The bodies were wrapped in nylon papers and reinforced with nylon ropes."
Witnesses had earlier reported that the bodies of nine men and women had been found.
Images on local television showed people gathered above the quarry using ropes to pull plastic sacks containing the human remains from rubbish-strewn water.
The Office of the Director of Public Prosecutions said it was "deeply concerned" about the discoveries "which point to a grave violation of human rights considering that the dumpsite is only a few metres from a police station".
It has directed the police to submit the results of their inquiry within 21 days, and also urged state agencies including the police oversight body to expedite investigations into reports of enforced disappearances and deaths allegedly committed by police.
Kenyan police are under scrutiny over the deaths of dozens of people during anti-government protests last month and reports of abductions of demonstrators.
The Kenyan Human Rights Commission, a non-governmental organisation, said a total of eight bodies had been recovered on Friday.
"KHRC is urging a comprehensive investigation to determine the cause of these deaths and identify those responsible," it said in a statement on X, formerly Twitter.
"The perpetrators must be held accountable."
Homicide detectives and forensic officers were at the scene, an abandoned quarry that was filled with water and used as a dumping ground for rubbish.
"We need answers from police because this is something that needs to be investigated very fast," said Lucy Njambi, who lives in Mukuru.
"It is shocking what I have seen. Bodies stashed in sacks and dumped at the dumpsite."
The DCI said preliminary investigations suggested all the victims had been killed in the same manner, without elaborating.
The bodies were taken to the city morgue to await postmortem examinations, it added.