Two explosions, at least one caused by a suicide attack, in the departure hall at Brussels Airport killed at least 14 people just before 8 a.m. local time, or 3 a.m. Eastern time.
About an hour later, an explosion at the Maelbeek subway station in central Brussels, not far from the European Union’s core institutions, killed at least 20 people and wounded more than 106.
• Was it terrorism?
Officially, Prime Minister Charles Michel of Belgium said there was no information about whether the attacks were related to the arrest last weekof the main surviving suspect in the assaults in and around Paris last year that killed 130 people.
The timing was noted by officials. “We were fearing terrorist attacks, and that has now happened,” Mr. Michel said.
The suspect arrested on Friday, Salah Abdeslam, is believed to be the sole survivor of the 10 men who were directly involved in the Paris attacks on Nov. 13.
• Why Brussels?
In addition to being the seat of European Union government and the capital of Belgium, Brussels has become a focus of counterterrorism investigations, notably since the Paris attacks.
Officials have also been concentrating on a particular Brussels neighborhood in an investigation of an Islamic State recruitment network.
Brussels has a high proportion of citizens who travel to Iraq, insular Muslim communities believed to have helped shield jihadists, and security services that have had problems with their counterterrorism operations.
• Who did it?
No claims of responsibility have been reported.
• What is Brussels like now?
The city, with a population of about one million, is virtually shut down. The Belgian prime minister is asking residents to “avoid all movement” as the authorities brace for the possibility of additional violence.
Flights to and from Brussels Airport, the city’s main international hub, are suspended.
All subway lines on the Brussels network are closed, as are the Eurostar trains that connect Brussels to London and the Thalys trains that link the city to other European capitals.
The European Union complex is locked down. Only employees with badges can approach the building.
• The reaction elsewhere?
Paris, London and New York are among the major cities bolstering security around their transit hubs and elsewhere.
President Obama, in Havana, offered American assistance to Belgium and said the United States would do “whatever is necessary” to bring the attackers to justice.
Condolences are coming in from around the world. The Eiffel Tower is to be lit with the colors of Belgium’s flag. Prime Minister David Cameron of Britain called an emergency meeting of ministers.
The German foreign minister, Frank-Walter Steinmeier, said the attacks “aim at the heart of Europe.”
“We are at war,” the French prime minister, Manuel Valls, said.
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