I was contacted via phone and set up an interview for the week after. I didn't know how many people I would be interviewing with, but speaking with three people in a group interview ended up not being that big of a deal. My interviewers were very friendly and answered all of my questions thoroughly. The place was very relaxed and people clearly got along well with one another, and were nothing but entirely friendly and helpful (and not in a fake way!) from the first interview until the point that I changed jobs.