NEW YORK – Divers in New York's Hudson River on Monday found the body of the eighth victim of a midair collision of a helicopter and small plane that killed nine people, but they were unable to dislodge it from the underwater wreckage, authorities said.

Five Italian tourists, the helicopter pilot, the plane's pilot, his brother and his nephew died on Saturday when the collision sent both aircraft plunging into the river that separates New York and New Jersey.

Seven bodies have been recovered, those of three Italian adults, two Italian teenage boys, the helicopter pilot and the plane pilot's 15-year-old nephew, authorities said.

An eighth body was found but not recovered on Monday, said Paul Browne, spokesman for the New York Police Department. He did not say which victim it was.

The body lies pinned in the wreckage of the plane below about 60 feet of water, Browne said.

The small plane had just taken off from the nearby Teterboro, New Jersey, airport at midday on Saturday when it collided with the helicopter, which had just lifted off for what was to be a 12-minute sightseeing flight.

New York Mayor Michael Bloomberg said the plane, a Piper Saratoga, appeared to hit the back of the helicopter, a Eurocopter AS350, which was operated by Liberty Helicopter, the largest sightseeing helicopter operator in the U.S. Northeast.

Pilots' first responsibility is to see and avoid, Bloomberg said. Sadly sometimes people make mistakes. I don't know in this case who made a mistake. That's for the (National Transportation Safety Board) to decide.

The NTSB is investigating the cause of the collision, which quickly prompted calls for more regulation of air traffic above New York's waterways that are major routes for small aircraft.

It's really too early to speculate as to what might have happened, said Debbie Hersman, chairwoman of the NTSB, at a news conference in New York.

Hersman said the NTSB has issued safety recommendations that have not been implemented by the Federal Aviation Administration. The FAA oversees U.S. aviation and sets rules for airspace use, while the NTSB investigates the causes of accidents and makes safety recommendations.

We believe that if those recommendations were to be implemented, aviation safety would be improved. I think the fact that we are here today shows that there is still a lot of work that needs to be done, Hersman said.

On average, 225 aircraft operate daily within a 3-mile radius of the accident site at or below 1100 feet, which was the elevation of the small plane in the collision, the NTSB said.

The crash occurred near the site where a US Airways jet with more than 150 people on board splashed down last winter after hitting a flock of geese. All aboard survived.

Bloomberg met with Italy's ambassador to the United States Giovanni Castellaneta, who said the collision occurred on the second day that members of a group of ten Italian tourists from the Bologna area took the helicopter ride. He asked for the inquiry to be prompt for the sake of victims' families.

The dead were identified as Michele Norelli, 51; his 16-year-son Filippo Norelli; Fabio Gallazzi, 49; his wife Tiziana Pedroni, 44; and their son Giacomo Gallazzi, 15.

New Zealand-born helicopter pilot Jeremy Clarke, 32, was also identified as a victim.

The bodies not recovered were those of the plane's pilot, Steven Altman, 60, and his brother Daniel, 49.

Daniel Altman's teenage son, Doug Altman, also died.

Witnesses' photographs showed one of the plane's wings came off in the collision, as did the helicopter's rotors.

Authorities said they do not expect to find recording equipment because small aircraft are not required to carry it.

In 2005 two helicopters, including a sightseeing flight, plunged into New York's East River but everyone on board survived. A year later, New York Yankees baseball player Cory Lidle and his flight instructor died when their small plane smashed into a Manhattan apartment building.

Two years ago, a sightseeing helicopter flown by Liberty Helicopters, which operated Saturday's flight, crashed into the Hudson River. Everyone survived.