The tour bus that crashed in northern Chile, killing 12 elderly American tourists returning to their cruise ship after an excursion, was unregistered and not authorized to transport passengers, government officials said Thursday.

The cruise line, meanwhile, said the excursion had been arranged privately and was not among those offered to its passengers.

Two Americans survived the crash but suffered broken bones and were moved to an intensive care unit at a local hospital as a precaution, according to Celebrity Cruises President Dan Hanrahan and a doctor in Miami.

The Chilean driver and tour guide also were hospitalized, but Juan Carlos Poli, a city hall spokesman in the Pacific port city of Arica, said they were in better condition and the guide was expected to be released Thursday. Poli said the bus had a capacity of 16 passengers.

The tourists — apparently members of a Jewish group on vacation from Connecticut and New Jersey — were returning to Celebrity Cruises' ship Millennium from an excursion to Lauca National Park Wednesday when the bus swerved to avoid an approaching truck and plunged off the rugged highway near Arica, 1,250 miles north of Santiago, he said.

The white bus tumbled more than 300 feet and ended up crushed and on its side. Rescue crews found the bodies of the victims spread out in the area along with some of their belongings, including local handicraft bags.

Hanrahan said the bus tour was not among those offered by Celebrity Cruises, which is owned by Miami-based Royal Caribbean Cruises.

"We don't know when they made the reservations (for the shore excursion). We do know they did not make the reservations on the ship." He said the company had not worked with the bus operator before.

The cruise line encourages guests to go on tours vetted by Celebrity because it puts contractors through a rigorous safety review, he said, but added, "What we can't do is tell guests what to do on their own time."

Chilean officials said the bus lacked permission to carry passengers.

The bus "was not registered with the Transportation Ministry," said Jorge Caceres, head of the ministry's office in the region where the accident occurred.

Pedro Mufeler, regional director of the government tourism agency, told The Associated Press by telephone that the small company, named Andinotours, had filed its request for registration some 15 days ago but it had not yet been approved. He did not elaborate.

The prosecutor in charge of investigating the accident, Manuel Gonzalez, said the driver may have fallen asleep.

"The investigation is still open, but we have an initial theory," he told Radio Cooperativa of Santiago. "Basically, a failure by the driver that may have been caused by the fact that he was tired ... apparently he fell asleep."

Hanrahan told reporters in Miami the victims — all in their 60s and 70s — were part of a 64-member B'nai B'rith group on vacation, but the cruise line was not releasing identities.

The cruise line said it was offering to fly family members of victims to Chile and was sending a special assistance team to the ship to help its guests and crew.

Eileen Marcus, an administrator at The Ponds, an age-restricted development in Monroe Township, east of Princeton, N.J., said several of those killed were residents of the development.

Marcus said she had received e-mails from others who were on the cruise and the bus trip and survived, but hadn't confirmed from them who in the community had died.

A rabbi said Ira and Linda Greenfield of Stamford, Conn., also were among those killed and their relatives were headed to Chile to identify the victims.

"Our thoughts and prayers are with the family during this difficult time," said Rabbi Daniel Cohen of Congregation Agudath Sholom. "Everyone is in a tremendous state of shock and sadness."

The Greenfields were longtime members of the synagogue. Linda Greenfield, 63, was a mentor at the local alternative high school and an active volunteer in the congregation, Cohen said. Ira Greenfield, 68, was a sales clerk at a television store.

Hanrahan said the injured tourists were in stable condition and were moved to an intensive care unit as a precaution. Dr. Mauricio Lynn of Jackson Memorial Hospital in Miami said one of the men broke a leg and the other broke a hand.

U.S. Embassy spokesman John Vance said consular officers were being sent to Arica.

The Millennium was docked in Arica. It had been scheduled to leave for Peru early Thursday, but the departure was delayed until the evening to allow guests to make other arrangements if they wished, Hanrahan said. The ship was carrying 1,536 guests and 920 crew members.

The ship was on a 14-night South American cruise. It departed Valparaiso, Chile, on Sunday and was scheduled to conclude in Fort Lauderdale, Fla., on April 2.

The accident occurred 25 miles northeast of Arica on the road leading deep into the high Andes Mountains, connecting the coast with the Bolivian capital of La Paz.