Five suspected gangsters were gunned down in Kitisuru on Friday morning and weapons found.
Nairobi DCI Chief Ireri Kamwende said police recovered three pistols.
He said the five had been on a robbery mission when officers from a special crime prevention unit ambushed them.
Meanwhile, Nairobi Regional Commissioner Kangethe Thuku has issued a 30-day notice for gangsters in the city to surrender their guns.
Speaking in Mathare on Monday, Thuku asked residents to embrace the Nyumba Kumi initiative and report criminal activities to police.
Residents were asked to use SMS code 22068 to report crimes at anytime for quick response.