The article below points to some of the reasons why this is happening.  From my limited perspective it appears that an underlying issue is lack of local schools on reserve forcing students to go to a larger community to continue their education.  Once there it appears supervision isn't adequate to prevent kids from getting involved with drugs or alcohol, and this seems to be a common factor in their deaths.  As tragic as this is, it's not within the purvue of the police to ensure young aboriginals are properly supervised when away from home.  It seems to me the feds, who  are responsible for aboriginal education need to step up and either provide greater funding for local schools or ensure proper supervision for kids who have to travel to continue their studies.\

https://www.theglobeandmail.com/news/national/jurors-find-deaths-of-three-aboriginal-youths-in-thunder-bay-ont-accidental/article30639523/