It happened around 5:35 p.m. near East 20th Street on Friday.
A passenger told Eyewitness News that the plane experienced a broken pontoon as it was taking off in Manhattan.
It then became disabled in the East River.
The FDNY says 10 people were taken off the seaplane.
They were taken to the 23rd Street Marina on the East Side. One of the passengers described her ordeal:
Passenger talks about being aboard seaplane when pontoon broke
The FDNY and NYPD Marnie Units gave a press conference describing the rescue.
It's believed that Bill Lawrence, the creator of "Scrubs," "Cougar Town" and "Spin City" was aboard.
He posted video of himself aboard the plane as it landed in the East River successfully on Thursday.
Here's his posts from Friday, his second flight in two days, below: