Don't worry about the police. You broke no laws whatsoever, and they have way bigger stuff to worry about. You might very well see these people again, but by then, it will have blown over. The woman who yelled at you might have even examined the situation (just as you are doing) and realized she over-reacted. And even if this is not the case, chances are, if you do see these people, esp. the woman, the worst that will happen is a cold look. Keep in mind that this woman's act of yelling at you had much less to do with you than it had to do with her past, her perceptions, her feelings.

Your request (though totally appropriate) possibly triggered something in her based on past experiences and emotions. It sounds as if she has issues w/ feelings of inferiority and/ or being bossed around by people (white people, it would seem, by your post). Her past issues are likely, considering that racism is still unfortunately part of society, as valid as your past issues being bullied. She just handled it very poorly and chose to unload on an innocent stand-in (you) for people or institutions who very well may have legitimately done this woman wrong. I hope this makes sense. Just try not to take it personally, as difficult as this may be to do. I am not excusing this woman's behavior at all, but one of my favorite quotations is "To Forgive All is to Understand All." As for you trying to explain your position, which was a noble thing to attempt, she was probably too blinded by indignation and too deep in her zone of anger to really hear what you were saying, or properly assimilate it.

Try not to worry about this situation or be too hard on yourself....