Four more bodies were pulled from the Hudson River on Sunday and divers searched for the other two victims of a collision between a small plane and a helicopter that killed nine people, including five Italian tourists.

National Transportation Safety Board officials said it was too soon to speculate on what caused Saturday's accident on a clear day over the Hudson River off Manhattan.

Searchers recovered the bulk of the wreckage from the helicopter in which the tourists had embarked on what was to have been a 12-minute flight around Manhattan. Officials said it would be taken to a nearby pier for examination.

The helicopter sustained significant damage, National Transportation Safety Board Chairwoman Debbie Hersman said.

She said seven victims had been recovered and searchers believed they had located the wreckage of the plane, which had taken off from nearby Teterboro airport in New Jersey minutes before the midday crash.

Within hours of the crash authorities said there was no hope of finding survivors among the five Italian tourists and a pilot aboard the helicopter and the three people on the plane.

Witnesses said the plane, a six-seater Piper Lance operated by Pennsylvania resident Steven Altman who was killed along with his brother and nephew, appeared to bank sharply before clipping the helicopter.

Photographs by witnesses showed one of the plane's wings came off after the collision, as did the helicopter's rotors, before both plunged into the river. Chunks of debris also fell on the New Jersey side of the river in Hoboken, narrowly missing motorists.

Italian media said the five tourists were from Italy's Bologna area. They were Fabio Gallazzi, his wife Tiziana Pedrone and their teen-aged son Giacomo Gallazzi, and Michele Norelli and his son teen-aged son Filippo. Jeremy Clark, a New Jersey resident who was piloting the helicopter operated by Liberty Helicopter, was also killed.

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

The search for victims and wreckage of Saturday's crash was hampered by strong currents and low visibility.

NTSB officials said they did not expect to find recording equipment in the wreckage because small aircraft are not required to carry it. They said investigators expected to be able to determine the cause of the crash by interviewing air traffic controllers and reviewing air traffic control and radar data as well as photographs and other evidence.

(Editing by Eric Beech)