Dozens of people are reported to have been killed or seriously injured in terrorist attacks at Brussels international airport and a city metro station.
Two exposions hit the departures area of Zaventem airport shortly after 08:00 local time (07:00 GMT).
Just about one hour later, another blast hit Maelbeek metro station.
The airport and whole transport system have been closed.
Belgium Prime Minister Charles Michel has described the attacks as "blind, violent and cowardly", saying they were a "tragic moment in our country's history. I would like to call on everyone to show calmness and solidarity".