Terror group Islamic State claim responsibility for Moscow concert hall gun attack said to have killed at least 40 people

A Russian serviceman secures an area as a large blaze is seen over the Crocus City Hall outside Moscow. (Photo/Moscow Times)

The Islamic State group claimed responsibility for a gun attack on a Moscow concert hall on Friday, which Russian authorities said killed at least 40 people.

IS fighters "attacked a large gathering... on the outskirts of the Russian…