The New York Post and Newsday say 20-year-old Ruslana Korshunova died Saturday afternoon in the Financial District. The newspapers cited unnamed officials and police.
The medical examiner's office later announced that her death was ruled a suicide.
Korushnova's New York agency and a spokeswoman for medical examiners did not immediately return telephone messages.
Originally from the former Soviet republic of Kazakhstan, the almond-eyed, flowing-haired Korshunova appeared in advertisements and on runways for such designers as Marc Jacobs, Nina Ricci and DKNY.
British Vogue hailed her as "a face to be excited about" in 2005.
Her break came when modeling booker Debbie Jones noticed her while perusing an in-flight magazine article about Korushnova's hometown of Almaty, according to the Vogue report.
She looked like something out of a fairytale!" Jones told the magazine. "We had to find her and we searched high and low until we did!"