Kenya security agencies have raided two houses in Eastleigh and Ruaka neighbourhoods barely a day after the attack at 14 Riverside office park that left nearly a dozen people dead.
During the operations, the detectives arrested two suspects in connection with the attack.
One suspect was arrested in Ruaka estate on the outskirts of Nairobi and the other in Eastleigh.
Director of Criminal Investigation George Kinoti confirmed the arrests.
Kinoti says one of the suspects only identified as Kemunto has been arrested in Mucatha, Ruaka, Kiambu County.
Kemunto has been apprehended at a house where one of the attackers is said to have been living for a couple of months.
Al-Shabab has since claimed responsibility for the attack which lasted for 20 hours.