rat fight

Question
I got two hairless rats from the animal shelter. (both male)  There were several, but i took only two.  I took them home, put them in the cage, with food and one water bottle.  All was fine, on the way home and everything, until we left the house.  When we got home they had been fighting, and were still fighting.  I separated them immediately, but one of them suffered a large bite wound between his shoulders, on his back.  I washed him off in warm water and put neosporin on the gash.  Both of them are scratched up.  I just don't know what to do now.  And why did they fight like this.  They lived together fine before.

Answer
They are very very stressed, obviously, and you do not know what kind of life they had before, unless you knew the previous owners?  How old are they and are you sure they knew each other and lived together before the were taken to the shelter?  

keep them apart for now, and let me know how old they are.  They may be aggressive and need neutered, depending on how they were bred.