Gov. George E. Pataki (R) announced that the state had suspended the licenses of a tour operator and a ship pilot here in this northern lake town, as investigators probed a boating accident that killed 20 senior citizens, mostly from Michigan.

"We have an obligation to make sure every stone is turned over to make sure we determined why this happened and take any action we can possibly take to prevent it from happening again," said Pataki, who stood with his back to a dense forest in this small village. "It's a tragedy of immense proportions."

The 40-foot-long Ethan Allen was carrying 48 passengers on a one-hour fall foliage cruise when it tipped in seemingly placid waters on a balmy Sunday afternoon on Lake George. It is not known what upended the small cruise ship, but survivors told authorities that as the boat turned, much of their weight shifted quickly to port, or left, side.

"That, of course, would automatically mean an even bigger shift of weight," said Mark V. Rosenker, acting chairman of the National Transportation Safety Board, which had a dozen investigators at the lake Monday.

Witnesses reported that the Ethan Allen was hit by a large wake, possibly generated by waves from another passing cruise ship. The pilot, Richard Paris, told authorities that he had tried to steer through this wake when his vessel tipped.

Because of reports that the boat lacked a second crew member, as required by state law for commercial vessels carrying 21 to 48 passengers, licenses for all five boats in the Shoreline Entertainment Complex fleet were revoked, said Wendy Gibson, spokeswoman for the state Office of Parks, Recreation and Historic Preservation.

The Ethan Allen was lifted from the lake bottom Monday afternoon, where it had been sitting upright in 70 feet of water.

The deaths resulted from hypothermia and drowning. Several of the elderly passengers had relied on walkers and canes, and no one was wearing a life preserver, officials said. Under New York regulations, which govern maritime rules at the lake, no passenger older than 12 is required to wear a life preserver. The Ethan Allen's maximum capacity is 50 passengers.

Jeane Siler of Monroe, Mich., who had traveled to Louisiana to aid victims of Hurricane Katrina before embarking on the foliage tour, spoke about the accident by telephone from her hospital bed.

Siler remembered sitting and talking with a friend on the ship Sunday. The next minute, she was floating in the water. She remembers the sound of people yelling and crying, and the pungent smell of diesel fuel pooling in the water.

"There was a small ridge [of the boat] that we were all clinging to," said Siler, 76. "They were scared; they were scared to death."

After a few minutes she took a deep breath and pushed away.

"I swam away," she said, "because I didn't want it to pull me down."

Five people remained hospitalized Monday, but most of the survivors boarded buses and headed home. Fourteen of the elderly tourists -- including three who died -- came from Trenton, south of Detroit. They were from a group known as the "Trenton Travelers," Trenton officials said.

Warren County Sheriff Larry J. Cleveland said investigators would contact operators of other cruise lines to determine if their boats played a role in the accident. Cleveland said Paris, the Ethan Allen's skipper, was a retired state trooper with at least 30 years of experience piloting cruise ships on the lake. The sheriff did not require Paris to submit to a drug and alcohol test, and described him as "pretty fragile."

"Strange things can happen on water," said Virgil Chambers of the National Safe Boating Council, which is not involved in the investigation. "If everyone goes to port or starboard, you can destabilize a ship in a hurry."

Powell reported from New York City.

Divers pull the tour boat Ethan Allen to the surface of Lake George, N.Y., where it capsized Sunday, killing 20 passengers, some of whom traveled in a group.