Four people have died after two unrelated avalanches in B.C. Sunday.Shortly before 1:30 p.m., the Terrace RCMP received a report of an avalanche on Mount Knauss that had impacted four heli-skiers. When search crews located them, three of them were confirmed deceased.A fourth person was airlifted off the mountain with serious injuries and taken to hospital.Then, in a separate event a couple hours later, Mounties in Atlin — over 1,000 kilometres away from the first event — received an SOS alert from a Garmin GPS device.The location of the alert was about 500 km from Atlin in an area near Klehini River and Pleasant Camp, near the border with Alaska.After a helicopter search, five people were found — one person was deceased and the four others were uninjured.In both cases, the BC Coroners Service was notified, and investigations are underway.