The 23-year-old victim, Sian Green, was struck in Rockefeller Center on Tuesday.
David Justino fashioned a tourniquet with his plumber's belt for one of Green's legs. He used a dog leash for the other injured leg.
TV's "Dr. Oz," who was walking in the area, rushed over when he heard the accident. He credited Justino for saving the woman's life.
A nearby food truck owner, Max Crespo, said he placed her severed limb in a bucket of ice.
Police say the cab driver was issued a summons for being an unauthorized driver. The circumstances of the accident are under investigation.
Take ABC13 with you!
Download our free apps for iPhone, iPad and Android devices
