Close encounter with non-human/meta human.

My sister and I had a very strange close encounter with a non-human.  
We were cutting through an alley to get to the local playground, and came upon a meta-human digging in a trash can.  She (seemed female) had a tall, lithe, figure, and a reptilian tail was visible out of the back of her/its long coat.  
It did not see us at that moment, and we witnessed it pull a milk cartoon out of the trash can, and began consuming the entire milk carton, tearing at the paper and eating it.  
Then, she/it saw us, turning her head, we saw her emerald green slitted eyes, and sharp teeth, when she hissed at us.  
We ran, afraid she would chase us.  
I have a clear memory of this event, and to my knowledge, it did occur, in the Fall of '76.
Witness indicates that the date of the event is approximate.  PD