Whoa!  Olessia and I are pretty sure the bird we saw was a hawk in our backyard.  I'm not sure if it was Cooper's Hawk or a Sharp-shinned Hawk.  Which ever hawk it was, it caught a local House Sparrow.  That hawk was a very impressive bird and had swooped in from out of nowhere.  Sorry, we didn't have enough time to get a camera.  As soon as we spotted the hawk, we saw it take off with the sparrow.