That sucks. I see these beasts all around where I live and they are always very shy and take off. There is an area near here where people have lost small dogs to them though, but that's a far cry from attacking a human.
One of the coyotes was shot and I imagine they'll test it for rabies...
Two coyotes in good health would never attack a human unless the there a den with pups nearby, but they'd rather lure you away with the wounded animal fein instead. Even hunger would drive them to get easier prey. She may have had munchies on her in a pocket or back pack.
My guess is rabies virus or neurological parasite.
There are coyotes in almost every major river valley in TO.