Five of the nine civilians suspected to be in possession of a self-propelled grenade along Thika Road were nabbed on Monday.
Four others are still at large.
Security agencies have been on high alert in a bid to thwart terror attacks before they occur.
On Tuesday, GSU officers foiled and Al Shabaab attack in Dabacity camp in Mandera.
Earlier on, a suspect Mohammed Nurrow Mohammedwas arrested in connection with a grenade attack that occurred along Latema Street in Nairobi on January 26, 2019.
Mohammed was later arraigned on Monday under a miscellaneous application where the police were granted three more days to detain him till investigations are completed.
“Intelligence reports show that he has other associates who assisted him in planning and executing the explosion,” the court heard.
The Director of Criminal Investigations had earlier released CCTV footage of a man believed to have aided the explosion.
The detectives appealed to the public to submit any information that would aid identify the man in the clip.
In the grainy footage, a man dressed in a black tracksuit and sandals was seen walking along the street with a carton in one hand.