Regina’s curse reached through realms to bring specific people she wanted.
I wouldn’t be surprised if this curses’s caster did the same, and he/she has a personal vendetta against Hook, Rump, and Regina (who doesn’t afterall?) and used the curse to bring them all there even if the ywere in storybrook.
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"I could have the giant duck as my steed!" --Daniel Radcliffe
Keeper Of Tamara's Taser , Jafar's Staff, Kitsis’s Glasses , Ariel’s Tail, Dopey's Hat , Peter Pan’s Shadow, Outfit, & Pied Cloak,Red Queen's Castle, White Rabbit's Power To World Hop, Zelena's BroomStick, & ALL MAGIC