Camouflage-clad gunmen opened fire at concertgoers with automatic weapons on Friday, killing at least 60 people and injuring 145 more in an attack claimed by Islamic State militants.In the deadliest attack in Russia since the 2004 Beslan school siege, gunmen sprayed civilians with bullets just before Soviet-era rock group “Picnic” was to perform to a full house at the 6,200-seat the Crocus City Hall just west of Moscow.