My 2 Female cats are hissing at each other?

I have 2 female cats, they are both 3 years old. Last night they started hissing at each other. They were fine in the day, but at about 8;45 P.M. they went ballistic and ones tail got really puffy and started hissing at the other really violently. It continued on through the night and all day today. We tried separating the food bowls, but the one that started the hissing comes over to the other cat trying to provoke her into fighting, can anyone tell me what might be going on???