I dont really agree. Out of all the people speculating on here, I dont think anyone mentioned the possibility of it being a bus.
Lots were thinking larger vehicle but probably discounted a bus due to the thought that it would have passengers. However, the buses really don't start rolling that early and it is a bit inconvenient for students during finals week that they don't. If you have a 7:30 final and want to get there early for some reason, they don't give you much time to do that.