Brussels' Zaventem Airport and a metro station near the heart of the E.U. were hit by explosions on March 22, sending the city into high terror alert. (Jenny Starrs/The Washington Post)

The Islamic State militant group said its fighters carried out the deadly attacks in Brussels on Tuesday, according to the SITE Intelligence Group.

The group published an audio recording in Arabic, promising "dark days" for all countries fighting against it "in response to their aggression against the Islamic State."

By the grace of Allah and His gratitude alone, a security detachment from the soldiers of the Caliphate, may Allah dignify it and support it, launched to target Crusader Belgium, which did not stop targeting Islam and its people. So Allah conquered through the hands of our brothers and cast in the hearts of the Crusaders fear and terror in the very heart of their land.

A group of the soldiers of the caliphate, wrapped in explosive belts and carrying explosive devices and machine guns, launched to target sites carefully chosen in Brussels, the capital of Belgium, to immerse inside Brussels airport and the metro station and kill a number of Crusaders, before detonating their explosive belts amidst their groupings. The result of the attacks was the killing of more than 40 and the wounding of no less than 210 of the citizens of the Crusader states, and unto Allah is all praise, gratitude, and grace.

We promise the Crusader states allied against the Islamic State with dark days, in response to their aggression against the Islamic State, and what is coming is worse and more bitter, Allah permitting. Praise be to Allah for His [granting of] security and success. We ask Allah to accept our brothers among the martyrs.

Before the group released its own audio recording, the Amaq News Agency, which is affiliated with the Islamic State, reported on the militant group's claim of responsibility for the Brussels attacks.

Islamic State fighters carried out a series of bombings with explosive belts and devices on Tuesday, targeting an airport and a central metro station in the center of the Belgian capital Brussels, a country participating in the international coalition against the Islamic State.

Islamic State fighters opened fire inside Zaventem Airport, before several of them detonated their explosive belts, as a martyrdom bomber detonated his explosive belt in the Maalbeek metro station. The attacks resulted in more than 230 dead and wounded.

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