Can USA B2 visitor apply for Canadian visitor visa from USA?

[w_bhai]

Hi,

My parents have approved/stamped USA visitor visa B2. They will be coming to USA this summer for few months. We are also planning to visit canada during that time too.

My question is - can my parents apply for Canadian visa after coming to USA or it will require resident proof in USA etc? Other option is to apply for visa in India. I would prefer to apply for it in USA if it is possible.

Please advice.