I initially thought sparrowhawk too, due to an encounter I had with one last year.
I came out of my house to witness a sparrow hawk tearing the insides out of a pigeon (which was still alive) on my front steps. I stopped in my tracks, the sparrowhawk looked at me with cold steel eyes as if to say, "Yeah? And? You want your face pecking off, pal?".
So, I ran back in the house and watched it from the front window instead.