How do I defeat the twilight creatures?

I just ped Eldin bridge in human(?) form. Not dog. I blew up some boulders and that caused some the bridge to blow up in the middle and some twilight creatures to generate. For some reason it won't let me do the B on circular field thing to kill them. I have no clue how to get rid of them now. Can some one tell me what I'm supposed to be doing?