A man selling toy helicopters near Columbus Circle got into a bloody box-cutter fight with another vendor Monday when he crashed his aerial gadget into the other man’s girlfriend, cops said.

Marcus Pagan, 38, was slashed in the neck by Carlos Perez, 48, at about 6:45 p.m. after Pagan flew the plaything into the woman’s head, according to police.

Pagan took out his own blade and slashed Perez in the forehead.

Both were charged with assault and were recovering at local hospitals.