Hawk Attack On my Pekins!!

Yesterday I let my two Pekin girls, Ping and Paddle, out to graze while I was getting ready to go. Luckily my husband looked out the window and noticed just one duck which he knew was weird because they are always together. He went outside to look and after a couple of rounds around the house saw a hawk on the ground where there is a ditch. He started towards it and it tried to take off with Ping but could not. He then heard Ping quacking and he ran towards them and the hawk let go and took off. Ping was fine, just a little shaken up which we both found amazing. We could not find any marks on her. We put them back in their pen and left and when we got home she was still just fine! I know that when I let them out to graze things can happen but I did not expect a hawk to try to get a duck as with them being as large as they are. When they were younger I never let them out without one of us there as I knew a hawk would go after a young one but once they were grown I didn't think a hawk would be a issue. Has anyone else had problems with them?