Oy!  Did you google and try to id it?  Maybe it was an eagle!  Surprising that the big ones would come into a neighborhood like that.   Neighbors near here had a red tail kill a big hen.  They chased it off so it never got to eat.  They have never given me and trouble, thankfully, but there are smaller ones who come through every so often that seem to be sizing up the big girls.  So far they have not gone after them, but they've been pretty small hawks.  Sharp-shinned was the last one.  Tiny.  I do worry about the Seramas, but they love being out so we risk it.