The incident happened in Coolock in the early hours of New Year's Day.
A lone male entered the premises armed with what is described as a handgun.
He demanded cash and then discharged a number of shots. Two male staff members, aged 38 and 28, received gunshot wounds.
Both men were removed to Beaumont Hospital where they are receiving treatment for their injuries which are not believed to life-threatening.
Gardai arrested two men in a follow-up operation.
A 44-year-old man remains in custody at Coolock Garda Station.
While a 16-year-old boy has been released without charge and a file is being prepared for the DPP.
Investigating Gardaí are appealing for witnesses or any person with information to contact the incident room at Coolock Garda Station on 01- 666 4200, the Garda Confidential Line 1800 666 111 or any Garda Station.
