The cause of the explosion is not confirmed, but early indications suggest a gas canister used in fire suppression systems exploded on site.
Two of the seven injured employees remain in a more serious, but stable condition and have been retained in hospital. The others have all been treated and discharged.
The project is being built by Crown House Data Solutions, a Laing O’Rourke company.
"This is a tragic event and our thoughts are with the family of our colleague who has tragically lost his life and with those who have been injured," said managing director of Crown House Liam Cummins. "I would also like to pay tribute to the emergency services who displayed exemplary professionalism in dealing with this incident."