Russia on Saturday said it had arrested 11 people – including four gunmen – over the attack on a Moscow concert hall claimed by Islamic State, as the death toll rose to 115. Camouflaged assailants opened fire at the packed Crocus City Hall in Moscow's northern suburb of Krasnogorsk on Friday evening ahead of a concert by Soviet-era rock band Piknik in the deadliest attack in Russia for at least a decade.