Police launched a manhunt after the perpetrators fled the scene of the firebombing in the Agouza neighbourhood of the Egyptian capital.
An initial toll had put the number of deaths at 12.
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A thick cloud of smoke was seen billowing from the fire-ravaged nightclub.
According to a security source, the attack appeared to have been the result of a dispute between employees of the nightclub and a group of youths.
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While Egypt is regularly hit by extremist violence, particularly targeting security forces, attacks on nightclubs are rare.
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