Why do white girls stare at me evil?

I was on a public transportation bus on a rainy day. I had to p this group of white girls standing in front of the bus. I mistakenly dropped my umbrella on this white girls toe while rushing off of the bus. I told her I was sorry yet her and her friends continued to stare me down evil. This isn't the first time that a white girl gave me a very evil stare out of the blue just for me minding my own business. It really hurts my feelings and can even ruin my day when I get theses stares. Why do white girls stare at me evil and what can I do to not let it bother me?