They had gathered to pray at Madina mosque in Mubi, Adamawa State; but in their midst was a brainwashed boy strapped with a bomb.

At least 50 people were killed and several others injured when he detonated the device.

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The U.S. in a statement by the spokesperson for the Department of State, Ms Heather Nauert, condemned the suicide attack saying it was an act of pure terror.

It extended sincere condolences to Nigerians and the families of the victims killed in the attack.

“That the victims were targeted and killed in a place of worship demonstrates yet again the brutal nature of the terrorists whose sole aim is to threaten the peace and security of Nigerian citizens.

“Such ruthless attacks on innocent civilians only serve to strengthen our resolve towards meeting these threats in cooperation with our Nigerian and regional partners," the statement read.

Madina mosque is in the Unguwar Shuwa area of Mubi that was liberated by troops in counter-terrorism operations over two years ago.

Also Read: Mubi Attack Is Cruel And Dastardly – Buhari

The attack is the worst recorded in a long period, as the military has decimated the terrorists in the north-east.

Regrouping members of the group that has pledged allegiance to ISIS have resorted to attacking soft targets.

President Muhammadu Buhari has also condemned the attack, calling it "cruel and dastardly".

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