Islamic State has claimed responsibility for two suicide bomb attacks in the Lebanese capital Beirut, which killed at least 43 people and injured more than 200.
The two detonations occurred less than 150 metres apart, and within five minutes of each other, in the residential Bourj al-Barajneh district, a stronghold of Hezbollah forces fighting IS in Syria.
The timing of the blasts is a common tactic in suicide bomb attacks, according to Lebanon's state-run National News Agency. Detonating two bombs is designed to kill people who converge on the scene of the first explosion to help the wounded.
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Lebanese Prime Minister Tammam Salam condemned the attacks as "unjustifiable" and declared Friday a day of national mourning.
One witness described the site as a "scene of chaos and carnage" with a "lot of shattered glass on the street" and "a lot of blood".
Another described the sound: "When the second blast went off, I thought the world had ended."
The body of a third bomber, who appears to have been killed by the second blast before he could detonate his own explosives vest, was recovered from the rubble.
According to a Lebanese security source speaking to CNN, a fourth would-be bomber survived the attack and has been taken into custody. He apparently told investigators that he was an IS recruit and that he and three other attackers arrived in Lebanon from Syria two days before.
Hezbollah said the bombing as "a Satanic terrorist act, carried out by apostates".
The BBC says the bombing is the worst in Beirut since the end of Lebanon's civil war in 1990. The country has seen much violence in recent decades, including a car bomb in the capital last year, for which IS claimed responsibility. According to the United Nations, the civil war in neighbouring Syria has contributed to intermittent violence near the border and has also led to more than a million people seeking refuge in Lebanon.
