A tour guide company that organized the trip for a large group of backcountry skiers that went missing after an avalanche near Lake Tahoe has broken its silence. Fifteen people are believed to have been hit by the terrifying slide on Tuesday morning as snow battered the region. Six were known to have survived, while nine remain unaccounted for. Mountain rescue launched a huge operation to find them on skis and snowcats, but have been struggling against horrific conditions that saw the entire region cut off. Blackbird Mountain Guides later said it had organized the trip for 11 clients and four guides at the Frog Lake huts in the Castle Peak area of the mountain.