At least 26 people have been killed or seriously injured in terrorist attacks at Brussels international airport and a city metro station.
Twin blasts hit Zaventem airport at about 07:00 GMT, killing 11 and injuring 81, the health minister said.
Another explosion struck Maelbeek metro station an hour later. Brussels transport officials say 15 people were killed and 55 injured, 10 seriously.
Belgium has now raised its terrorism threat to its highest level.
The attacks come four days after Salah Abdeslam, the main fugitive in the Paris attacks, was seized in Brussels.
Prime Minister Charles Michel called the latest attacks “blind, violent and cowardly”, adding: “This is a day of tragedy, a black day… I would like to call on everyone to show calmness and solidarity”.
European Council president Donald Tusk said: “These attacks mark another low by the terrorists in the service of hatred and violence.”
The airport and the entire public transport system in Brussels are closed.
‘Blood everywhere’
Two blasts tore through the departures area of Zaventem airport shortly after 08:00 local time (07:00 GMT).
The Belgian prosecutor said “probably a suicide bomber” was involved.
The state-owned Belga news agency reports that shots were fired and shouts in Arabic were heard before the two explosions.
Public broadcaster VRT said an assault rifle was found next to a dead attacker.
