An avalanche cascaded down a Canadian mountainside Sunday afternoon, injuring one skier seriously and possibly leaving up to four others missing, police said. Royal Canadian Mounted Police Cpl. Grant Simpson said the avalanche occurred outside the boundary of the Panorama Mountain Village in the Purcell Mountains near Invermere, British Columbia. Simpson said search teams had been assembled to try to find any skiers who may have been trapped by the snow slide, the Canadian Broadcasting Corp. reported. The Vancouver Sun reported two skiers -- a woman with possible spinal injuries and a man with no serious injuries -- were rescued, but that up to four others may have been buried. Simpson said, however, it was \"quite possible\" all skiers in the vicinity had gotten out of the avalanche\'s path, the Sun said.