Law enforcement sources tell TMZ Rihanna's injuries were severe -- two "huge contusions" which swelled up on both sides of her forehead. We're told she also suffered "a bloody lip and nose."

One of the law enforcement people put it this way -- the contusions "look like an MMA fighter or something ... [It] looked like she was growing devil's horns."

We've also heard that Rihanna may have suffered bite wounds on one of her legs and arms, however, one source close to the situation tells us he doubts that is the case.

Chris Brown has been booked on a felony criminal threats charge. If the D.A. files the case, domestic violence charges could be added.
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