The small plane was carrying a man and a woman on a sightseeing trip, and crashed about 5:20 p.m., Yonkers Police Lt. Phil Collins said. The two were wearing life vests and were able to get out of the plane before it sank, Collins said.
The cause of the crash was under investigation.
The couple were plucked from the waters within 30 minutes of the crash and taken to Jacobi Medical Center. They were treated for hypothermia and were listed in stable condition at Jacobi, Lt. Toni Scherer of Empress Ambulance Service said. The names of the two were not immediately released.
Federal Aviation Administration spokeswoman Kathleen Bergen described the plane as a Piper PA-32. Bergen said the pilot told local authorities the flight left from the Trenton-Robbinsville Airport in Robbinsville, N.J. It was flying under visual flight rules and not receiving air traffic control services, she said.
The Journal News reported that Yonkers police officers and a retired detective took a boat out to rescue the two.
"Thank God we got there quick enough," said Daniel Higgins Sr., an off-duty police officer who piloted the boat and whose 12-year-old son was aboard and helped in the rescue effort.
"It's what we do for a living, and I'm just glad we were in the right place at the right time," Higgins told the News.
The plane was registered to Dominick Lipariti, of Manalapan, N.J., according to FAA records. A man who answered the telephone at Lipariti's home told The Associated Press that it was his son's plane and that it had been sold to someone else. He declined to identify the buyer.
In 2009, Capt. Chesley "Sully" Sullenberger safely landed US Airways Flight 1549 on the Hudson River in New York after striking a flock of geese. All 155 people aboard survived.