Russia on Saturday said it had arrested 11 people, including four assailants, involved in the Moscow concert hall attack and reported a new death toll of 93, which it warned could rise. Friday evening’s attack, which was claimed by the Islamic State, is the deadliest in Moscow for at least a decade. The Kremlin said the head of Federal Security Service (FSB) had informed President Vladimir Putin about the arrests on Saturday. “FSB Director Alexander Bortnikov reported to the president on the detention of 11 people, including four terrorists involved in the terrorist attack at Crocus City Hall,…