Work visa for USA - from Canada (Toronto)

Hello everyone,

I am originally from Ukraine currently living in Canada as an international student (non-citizen, non-permanent resident). So far as I know international students in Canada can apply for US visa type B1/B2. I am just wondering, if it is possible to apply for working visa in USA? Or sponsorship from employer is required?

Any advices, recommendations, documentation, any information would be appreciated.

Thanks
Aleksey