A search for victims of the fatal mid-air collision between a tour helicopter and a small plane on the Hudson River off New York City has been suspended until morning, the NTSB said, with three of nine apparent victims already pulled from the water.
Everyone aboard both aircraft that collided shortly before noon are believed dead, officials said.
"I'm sad to report that at about 12 o'clock this afternoon there was an accident, which we do not believe was survivable," New York Mayor Michael Bloomberg told reporters.
"This is not going to have a happy ending like when the Airbus went down on the river where everybody survived," Bloomberg added, referring to the case in January when a disabled passenger plane landed safely on the Hudson. "In this case, we believe nobody has [survived]."
The helicopter operated by Liberty Tours was carrying a pilot and five Italian tourists, and the plane carried three people, including a child, Bloomberg said.
The plane's pilot was Steve Altman, who was taking his brother David and David's teenaged son to the beach, ABC News Radio reported.
The helicopter occupants were two male teens, three adult men including the pilot, and an adult woman, ABC News station WABC in New York reported.
At least two bodies were pulled from the water by mid-afternoon, and the rest of the passengers were presumed dead, Bloomberg said. A third victim was pullled from the water later before the search was suspended, WABC reported.
The three bodies were believed to be two males from the helicopter and a third male, possibly the child who was on the plane.
Earlier, officials said at least six survivors, perhaps seven, were plucked from the water and were being treated by emergency medical technicians in New York City, but those reports were incorrect, the New York Fire Department later said.
According to the Federal Aviation Administration, the Piper airplane was headed from Teterboro, N.J., to Ocean City, N.J., and the Liberty Tours chopper had just taken off from New York's 30th Street Heliport.
"It would appear that the airplane ran into the back side of the helicopter," Bloomberg said. "But keep in mind with all of these things that, number one, until the National Transportation Safety Board [NTSB] makes the determination, nothing is a fact."
He said an NTSB investigation could take weeks or years.
The NTSB had local investigators on the scene, and also was sending a team to the site from Washington, D.C., that included Chairwoman Debbie Hersman.
"We are going to be looking very closely at air traffic control tapes and information about where those two aircraft were, and any air traffic communications that occurred prior to the collision," Hersman said before departing.
The FAA earlier said the helicopter hit the fixed-wing aircraft near New York's Pier 57.
"I saw a puff of smoke," Alanna Duffy told ABC News Radio after seeing the accident from a New York pier. "And then the helicopter did a couple of twists and turns, and rotors started flying. And then the nose of the helicopter went straight down into the water."
A debris field, including a fuel slick, spread across the Hudson River, much of it toward the New Jersey side. Debris, including a wheel, washed up in New Jersey.
Police initially set up a security cordon both north and south of the crash site, located just south of 14th Street. Within minutes, divers and vessels attempted to rescue occupants of the submerged aircraft.
"Paramedics bringing someone from the plane/helicopter crash onshore at Pier 40. Cop cars/fire trucks everywhere," one tweeter wrote on Twitter, quoting the user "mikomercer."
Later, a large crane on a barge moved toward the debris field.
Bloomberg said this afternoon that the wreck of one aircraft had been found toward the New Jersey side of the river.
"We believe it is the helicopter," he said, "but the visibility is about two feet at a depth of 30 feet."
The second aircraft, believed to be a Piper Saratoga, was not initially located.
"Unfortunately, there's not a lot of rescue to be done here," Bloomberg said. "It's all recovery from this point on."
Air traffic controllers at Newark International Airport reported that they lost radar contact with the Piper airplane around noon, said Jim Peters of the FAA.
The Newark tower monitors air traffic on the part of the Hudson River where the accident occurred. However, planes and helicopters can fly that corridor below 1,100 feet under visual flight rules and bypass direct control by controllers. Such craft must "see and be seen," and it is their responsibility to avoid other aircraft.
Planes flying south, as this one was, are required to fly along the New Jersey side of the Hudson River.
New York Gov. David Paterson vowed to work closely with city and federal investigators to get to the bottom of the crash, which he called "a tragic accident."
"As we continue to monitor the progress of the recovery efforts, our hearts and prayers go out to the families of those who were on board each of these aircrafts -- both here in New York and in Italy," Paterson said in a prepared statement. "What began as a beautiful day with blue skies has turned into a day of darkness for those who lost someone they love today."
ABC News' Aaron Katersky, Dan Gura, George Sanchez and Stephanie Sy contributed to this report.