New York City's office of emergency management urged people nearby to close their windows and avoid the smoke, and warned of traffic delays near the area.
The blaze broke out at the Helen L. and Martin S. Kimmel Pavilion, which is under construction and scheduled to open in 2018, authorities told local media.
No injuries have been reported.
Images and video posted to social media showed plumes of black smoke and large flames ripping through the roof of the building on First Ave and East 30th Street.
Manhattan **66-22-0684**2nd Alarm** @NYULMC NYU/Langone Medical Cntr 560 1st Ave off E. 30 St. E-16/TL-7 1st due. pic.twitter.com/LS8pZj3fLm
#FDNY members on scene of 2-alarm at NYU Hospital 30th St & 1st Ave pic.twitter.com/p5FlvUeAxP
- FDNY (@FDNY) December 14, 2016
Manhattan heavy fire out the windows 5th floor of NYU. pic.twitter.com/u8tCZjgzWq
- New York City Alerts (@NYCityAlerts) December 14, 2016
Update; 2nd alarm Manhattan at NYU Medical Center, division 1 reports they have water on the fire. Remains doubtful. pic.twitter.com/E00OXzeGKT
- New York City Alerts (@NYCityAlerts) December 14, 2016
This story is developing.