NEW YORK (CNN) -- The bodies of two adults and one child were recovered Saturday after a tour helicopter collided with a small plane over the Hudson River, authorities said.
The two adults were from the helicopter, which was carrying five Italian tourists and a pilot, New York Police Deputy Commissioner Paul Browne said.
The child is believed to be one of three people aboard the plane, which has not been located, Browne said.
All nine people are thought to have been killed in the collision, which occurred around noon over the Hudson between New York and Hoboken, New Jersey, said New York Mayor Michael Bloomberg.See where the collision occurred »
"There was an accident which we do not believe was survivable," said Bloomberg, noting that the search for survivors had become a recovery mission.
The plane was a single-engine Piper PA-32, which apparently took off from New Jersey's Teterboro Airport shortly before the collision, the mayor said.
The helicopter was an American Eurocopter AS350 operated by Liberty Helicopter Sightseeing Tours, Bloomberg said. PhotoView images from the scene »
Relatives of the victims were receiving counseling, he said.
Preliminary reports indicated the airplane ran into the back of the helicopter, Bloomberg said, but warned that no official information was yet available. iReport.com: Police search for debris
"Until the National Transportation Safety Board makes its determination, nothing is a fact," he said.
At least one piece of wreckage was found, but the murky waters of the Hudson, where underwater visibility is about two feet, hampered divers' efforts, Bloomberg said.
Witnesses reported seeing debris flying from the helicopter as it crashed.
The recovery mission was called off around 6:30 p.m. Saturday and was scheduled to resume Sunday morning, authorities said. A temporary flight restriction over the rescue area -- about three nautical miles around and 2,000 feet up -- was put in place, a Federal Aviation Administration spokeswoman said.
Witness Arnold Stevens said after the plane had a wing sheared off, it began "corkscrewing" into the water. The helicopter "dropped like a rock" after the collision, which happened about noon. VideoSee a series of photos from the scene »
Radar contact was lost with a small plane this morning believed to be the aircraft in the crash, FAA spokeswoman Arlene Salac said.
Ben Berman, a former investigator with the National Transportation Safety Board, said if the helicopter fell straight down, it's likely there was a rotor failure.
Scott Schuman was with his grandparents on the Hoboken side of the river when they heard a loud bang.
"The plane was kind of whirlybirding its way down, brown smoke coming out the back of it, and it crashed into the water. Then a few seconds later the helicopter with debris falling off of it also hit as well," Schuman said.
"It was a scary sight," he added. iReport.com: Were you there? Send images
He said some of the debris fell in Hoboken, and "we covered our heads."
Asked if he had seen anyone in the water, Schuman replied, "I have not seen anything, but judging by the impact when the plane and the helicopter hit, it would be very unlikely for a positive outcome."
Hoboken Mayor Dawn Zimmer called on witnesses who filmed or photographed the incident to come forward.
"It would be extremely helpful to have that footage," he said.
The busy airspace surrounding New York's Manhattan island has been the site of several aeronautical mishaps in recent history.
Earlier this year, a US Airways plane with 155 people on board ditched into the Hudson, apparently after striking at least one bird upon takeoff from New York's LaGuardia Airport, officials said.
Capt. Chesley B. "Sully" Sullenberger's landing, which resulted in no deaths or serious injuries, was captured on closed circuit television.
In 2005, Yankees pitcher Cory Lidle and his flight instructor were killed when the 34-year-old ballplayer's plane crashed into a high-rise apartment building near the East River, city officials said.
