A suicide bomber detonated his device in departure hall of Brussels Zaventem airport, causing multiple deaths and many injuries, and a second blast struck Maalbeek Metro station in the capital shortly afterwards. The Belga agency said shots were fired and there were shouts in Arabic shortly before the blasts at the airport. Pictures show smoke rising from the terminal building through shattered windows and passengers running away, many hauling their luggage.

The Metro station hit by the explosion was close to European Union institutions. Authorities closed all metro stations in Brussels.

The blasts at the airport and Metro station occurred four days after the arrest in Brussels of a suspected participant in November militant attacks in Paris that killed 130 people. Belgian police had been on alert for any reprisal action.

Attentats à #Bruxelles "Le Roi et la Reine sont choqués par les événements" (Palais) https://t.co/V63LyIO0R3 pic.twitter.com/S9EPFHbCQc

— lalibre.be (@lalibrebe) March 22, 2016

Notre metro bien connu... Image choquante de #maelbeek ... pic.twitter.com/XhgB71RM0P

— ᴀʟxᴅᴍ (@alxdm) March 22, 2016

Feared death toll of #Brussels explosions increased, as reports claim 21 or 23 people killedhttps://t.co/N3WEKvbiiV pic.twitter.com/2YRYkVLz4A

— TRACterrorism.org (@TRACterrorism) March 22, 2016

Flags being put at half mast outside European Commission. #brussels pic.twitter.com/QAQCNgjUbu

— Imelda Flattery (@Imeldaflattery) March 22, 2016

The Maelbeek metro attack is around 350m from where EU leaders meet for summits in Brussels pic.twitter.com/uncVsxOBoS

— Alex Barker (@alexebarker) March 22, 2016