Flying Squad trailed the gangsters from Kiambu.
Four suspected gangsters were on Thursday morning shot dead at Cabanas on Mombasa Road in Nairobi.
Nairobi County Police Commander Japheth Koome said officers from the Flying Squad trailed the gangsters from Kiambu.
A pistol and a revolver were found.
A Ceska pistol and revolver, each with nine rounds of ammunition, were found in the 3.20 am incident.
Police also found a magazine with 10 bullets and detained a motor vehicle the four were travelling in.