The LA Times gets it:
Authorities trace the violence to the recent government crackdown on cocaine traffickers in Mexico, which has squeezed profit margins for cocaine north of the U.S. border.
Canada's outlaw retailers are fighting to the death over market share, police say, a situation exacerbated by personal vendettas and power vacuums left by the arrests of gang leaders.
"The war in Mexico directly impacts on the drug trade in Canada. . . . There's a complete disruption of the flow of cocaine into Canada, and we are seeing the result," said Pat Fogarty, operations officer for the Combined Forces Special Enforcement Unit, British Columbia's main law enforcement agency targeting organized crime.