Urgently need a sitter-how to find?

I need to have a super reliable sitter to get kids from school and then stay with them until I return, for 2-3 weeks probably during April. I am not sure how to go about finding someone who is 1) super reliable 2) super trustworthy. I will be entrusting both my children, and also the house keys so feeling very uneasy. How do others do it? Do you hand your keys over? Do you find someone through agencies? I am in Waterloo. Thanks in advance for any advice and suggestions, this is hyper urgent.