National Guard helicopters fighting tricky canyon winds today removed the charred bodies of all 25 victims of Wednesday's airplane-helicopter collision over a remote section of Grand Canyon.

Seachers at the crash site said the victims, who were enjoying an early morning sightseeing flight when the aircraft collided, were burned almost beyond recognition.

"What we basically had here was a crematory," said Sgt. Steven Luckesen of the Coconino County Sheriff's Department. Luckesen said the post-crash fire was so intense that aircraft parts were smoldering 24 hours later.

There was no immediate explanation for the collision, which occurred in clear, calm weather in an open section of the vast chasm. The plane, a deHavilland DHC6 Twin Otter, and the helicopter, a Bell 206, were near standard sightseeing flight routes at the time.

National Park Service officials said the helicopter's rotor evidently cut into the bottom of the plane as the two craft flew near a towering red rock formation known as "Confucius Temple."

Both craft then plummeted to fiery destruction on Tonto Plateau, a rocky desert mesa covered with yucca and prickly pear. The crash site, on a sloping ridge some three miles north of the Colorado River at the heart of the canyon and about 3,000 feet below the canyon rim, is so remote from Indian settlements and hiking trails that the victims may have been the first humans ever to touch ground there.

Most of the victims were European tourists, and Sheriff's Deputy Jack Judd said late today that the five people on the helicopter and 17 of the 20 on the airplane had been tentatively identified. A complete list was not available, but two of the airplane passengers were identified as Sherry Goss of Joppa, Md., and her mother, Florence Whittenburg of Mountain Home, Ark.

The National Transportation Safety Board set up an investigation center in Grand Canyon Village to begin searching for causes of the crash. But board officials said that, because of treacherous wind conditions in the canyon, it would be at least a day before they could fly to the site to gather clues.

The aircraft that collided had both taken off from Grand Canyon Airport for standard tourist flights. Both were flying below the canyon rim at the time of the collision, and were operating under "see and be seen" flight rules.

The accident seems certain to renew calls in Congress for more intensive Federal Aviation Administration surveillance and stronger regulations for sightseeing operators. The FAA excludes from more stringent safety requirements planes that limit their flights to within 25 miles of one airport.

Helitech Inc., which has been in operation about two weeks, was flying its sightseeing helicopter under that exclusion, safety board spokesman Michael Benson said in Washington. He said it is possible that the plane, owned by Grand Canyon Airlines, was also operating under the lesser standard, although that information was being checked and the airline is known to meet the regulatory requirements for a full-fledged commuter airline.

Park officials said there have been nine other fatal crashes of small aircraft here in the past five years, with Wednesday's crash the worst.

Some sightseeing lines continued to fly today, and sightseers continued to line up at the little airport just south of the canyon.

"We've been planning for a long time to fly over the canyon, and we're going to do it," said Brad Algood, a Californian who bought $35 flight tickets this morning for himself, his wife, and his three children.

"Look," he said, "I'm more likely to get crunched out there on the street in my Volkswagen than to have this plane go down."

Searchers probing the wreckage said both aircraft must have exploded into flame as soon as they hit the ground, dousing their passengers with burning aviation fuel.

The searchers said remains of the 20 people who had been on the plane were found neatly lined up as if seated in an airplane -- but that the seats they were on had completely melted in the conflagration.

Staff writer Douglas B. Feaver contributed to this report.