I looked at HR and Guillotine there's nothing specific that's been reported beyond what's been reported in the links posted here. I do see a lot of speculation in those places, and here, about it being related to a hazing incident, mostly due to mention of an object, but that's really not a lot to go on.
I do find it odd that they're still in custody and haven't been charged, which could mean that the prosecutors are debating how to proceed (Do they have the facts? Which statutes apply?), or that they couldn't find a prosecutor over the weekend.
Still very little to go on.
FWIW, the victim's gender probably won't make a meaningful difference with respect to the a assault statutes, though I imagine it'll be perceived differently politically if it turns out to have been a hazing incident.