You need to get in contact with your local Humane Society. They can and will give you the best advice.
They may be feral cats, which is not unusual anywhere. Perhaps theres a feral cat orgainization in your area, start googling.
In the meantime here is a link for you to the Humane Society. Good luck, so sad I know. I can't pass anything up human or animal when I know somethings wrong, little defenseless kitties (although I'm allergic) really tug at my heart.
The Toronto Humane Society
Take care.