A spokesperson for the city's metro system says at least 20 people have died in a bombing at a station near the EU headquarters.
While two blasts at the city's main airport before that killed up to 14 people, according to local media reports.
All flights are now suspended, and people are being told to stay away.
The Department of Foreign Affairs says anyone concerned for family or friends in Brussels can phone a Dublin number 01 418 0200.
All flights to and from Zavantem airport have been cancelled until tomorrow morning.
However flights through Brussels Charleroi are running, with some delays at the airport.
Both Ryanair and Aer Lingus are offering refunds and changes to customers.
Facebook has activated its “safety check” system to help people track friends and loved ones in Brussels.
Acting Taoiseach Enda Kenny, says the attacks were an attack on democracy.
The Metro blast was near the EC offices in Brussels – Dermot Ryan from Tipperary Town was inside the Berlaymont building when the explosion happened.
Speaking on Tipp Today with Fran Curry he says they are in virtual lockdown at the moment.
The Belgian prime minister says there's no information as to whether this morning's killings are related to last week's arrest of the main suspect in November's terror attacks in Paris.
However Sean Kelly MEP who flew back into Brussels last night told Tipp Today this morning that security appeared to be high in the past 12 hours.
