I don’t know, but I think it’s likely that they’re seeking asylum. These are smart, upper-class kids from a largely Christian nation. Makes sense that they’d try for Canada, because they may very well speak French; and they may perceive Canadian immigration regulations as less strict than ours.
I don’t know how the visa issues will translate - they may be sent back to the US (?)
https://www.freerepublic.com/focus/f-news/3570671/posts
2 members of missing Burundi robotics team spotted crossing into Canada