It's not so much about whether it is possible, but more about whether you are able. For some people, studying is all they have time for, and others would rather have a social life than work. It really depends on the individual. Personally, I am in my second semester (in class and my first clinical placement), and I am still working.
If you are going to work though, I think that doing it through the school is a great choice. They will be a lot more accommodating with schedules, etc than any other employer, and you're already on campus.
