Several explosions have struck Brussels airport and the metro system, causing at least 13 deaths, morning international media reports say.
Two explosions are understood to have ripped through the departures area of Zaventem airport shortly after 08:00 local time (07:00 GMT).
An hour later, an explosion hit the Maalbeek metro station at rush hour, close to the EU institutions.
There are unconfirmed reports of a potential fourth closer to the parliament buildings, with the Belgian Government raising terror security levels to their highest point.
The attacks come just four days after Salah Abdeslam, the main suspect in the Paris attacks, was captured in Brussels.
The Belgian government has confirmed casualties but has given no exact numbers.
The cause of the explosions is also unknown. Both the metro system and airport have been closed.