Does anyone know how to remove blood stains?

I leaked a bit on my pants and was walking for who knows how long around school. My only consolation is the fact that the stain was still somewhat wet when I got home, so maybe it leaked during my last class or on the bus headed home and maybe only 5 people, at most, saw the stain. I really hope so at this point. Of course it happens the one day I decided not to loosen my backpack enough to cover my rump. (My rump is one of my insecurities. So, if I can hide it than I'm hiding it. This incident just strengthened my resolve to.). Also, at this moment, I'm somewhat glad I'm 5ft tall. In the crowd of others trying to get out, only those below 5ft could've seen without much hassle. From the distance though... I just hope it happened on the school bus. I need to buy more oversized sweaters or black jeans. I dislike my life.