I saw a crocodile in my dream which swallowed away my sister?

I saw a crocodile in my dream which swallowed away my sister (pregnant or 7months now). I saw the crocodile and hence i did not get into the water and when i turn around and look for my sister i suddenly see her in the water and it swallows her. I was so scared for a long time and could not close my eyes for almost 1 hr after this dream. I felt as if it happened really in front of my eyes. Pls tell me what this indicates.