Acting on a tip-off, the suspects - identified as Khayyum Sheikh, Ahmed Munsi, Sajid Servar Khan and Adnan Sayyed - were nabbed from near Marathi Mandir theatre in central Mumbai this evening, said ATS chief Rakesh Maria.
They have been handed over to Crime Branch, which in investigating the May 17 incident, he said.
Sheikh and Munsi are suspected to have supplied weapons to the shooters, while the other two acted as watchers at the time of the incident, he said.
On Tuesday, two gunmen, 29-year-old Syed Ali, a resident of adjoining Thane, and Indra Khatri (27) from Nepal, allegedly shot dead Kaskar''s driver-cum-bodyguard Arif Syed Abu Bukha (40) in south Mumbai''s Dambarwala building. The building houses Kaskar''s office and house.
The two assailants were later arrested from near J J Hospital, a short distance from the shooting site, while their two associates managed to escape. Those arrested are in police custody till May 26.
Underworld don and Dawood's arch rival Chhota Rajan''s name had also cropped up during preliminary probe into the incident.