You should be very careful. All hawks and owls are federally protected with stiff penalties if you are caught.
http://icwdm.org/handbook/birds/HawksOwls.asp
Normally, that is true unless they are attacking and you have exhausted non-lethal means to drive the predator away. This hawk wouldn't stop even then I was standing over him. Like Danz said a hawk will usually fly away and watch from afar. I could even get my girls back in their coop without this little devil attacking them. It was crazy!