Azimio leader Raila Odinga has cancelled his planned Kamukunji rally on Wednesday.
Raila said the decision was arrived at after they received intelligence that the police planned to use live bullets during the rally.
He said some of their staff were deployed to set up the stage at the Kamukunji grounds and were attacked by the police on Wednesday morning.
He said some of their workers were also arrested on the grounds.
"Yesterday night, we received intelligence of a very heinous plan by Kenyan Kwanza to ferry goons who would attack peaceful attendees of our rally in Kamukunji. These goons had express order to shoot directly to the crowd while enjoying police protection," Raila said.
"Early this morning, our crew who had been sent to set up the stage at Kamukunji were attacked and their equipment damaged. Some were arrested. In line with the intelligence we received, armed goons have this afternoon descended on Kamukunji and shot indiscriminately into the crowd."
Raila insisted the Azimio protests have always been peaceful, but have been accompanied by injuries and possibly deaths because of police involvement.
He said Kenya is slowly degenerating into a police state, and this should not be allowed to happen.
"Police have shot, injured and killed protesters in various parts of the country including here in Nairobi. Scores of protesters have been arrested for participating in an exercise that is clearly protected by the constitution. As usual, it is the police maiming and killing people.
"We have always said that these meetings remain peaceful until police decide to break them up with bullets and teargas," Raila added.
He noted two instances on Monday and Tuesday where he interacted with city residents in the Central Business District and Kenyatta Market and it was all peaceful, because police did not interfere.
