Many people have been killed or seriously injured in terrorist attacks at Brussels international airport and a city metro station, Belgium's PM says.
Two explosions hit Zaventem airport at about 07:00 GMT, and another struck Maelbeek metro station an hour later.
The government has not confirmed casualty numbers. Brussels transport officials say 15 died at Maelbeek and media say up to 13 died at the airport.
Belgium has now raised its terror 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 Brussels attacks "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".
The Belgian prosecutor said it was "probably a suicide bomber" who struck the airport.
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The airport and whole transport system are closed.
European Union president Donald Tusk said: "These attacks mark another low by the terrorists in the service of hatred and violence."
'Blood everywhere'
Two blasts tore through the departures area of Zaventem airport shortly after 08:00 local time (07:00 GMT).
The Belga news agency reports that shots were fired and shouts in Arabic were heard before the two explosions.
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A key suspect in the attacks in Brussels has been arrested, Belgian media say, quoting judicial sources.
Najim Laachraoui, thought to be the man on the right in a CCTV image taken before the Zaventem airport attack, was detained in the Anderlecht area.
Two of the other attackers have been named in Belgian media as the brothers Khalid and Brahim el-Bakraoui.
Twin explosions at the airport and another at a metro station on Tuesday left about 34 dead and 250 wounded.
There has been no official confirmation of the latest arrest or the identity of any of the attackers.
I haven't any news of Adam but let's hope he's OK.... Never stop dancing buddy.. 
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Yes, where are we now? Just name the city, the river and what is the mostly spoken language in this city? Wishing you all a very nice Saturday night, Cheers Boys:)))
