A tour boat that capsized on a New York lake, killing 20 people, did not have the required number of crew members aboard, leading state regulators to suspend licenses for all five vessels belonging to the company that operated the tour, officials said Monday.

The Ethan Allen (search), which overturned Sunday on Lake George (search) while carrying 47 elderly tourists, was required by state boating regulations to have two crew members, said Wendy Gibson, spokeswoman for the state Office of Parks, Recreation and Historic Preservation.

Any commercial boat that carries 21 to 48 passengers must have two crew members, she said.

Authorities have said the only crew member aboard was Capt. Richard Paris (search).

"If that's the case, there's going to be a problem, and it looks like that's the direction this is headed in," Warren County Sheriff Larry Cleveland said.

Earlier in the day, officials had said state rules allowed for just one crewman for up to 50 passengers.

State regulators originally suspended the licenses for two small boats similar to the Ethan Allen, but Gibson said they had expanded the suspension to include two larger vessels that carry 400 and 200 passengers, compared with the smaller boats that carry between 30 and 50 people.

Earlier Monday, authorities said the passengers aboard the tour boat were sitting on long benches and slid sharply to one side of the vessel just before it flipped over.

State police Superintendent Wayne Bennett said that investigators do not know what initially caused the Ethan Allen to tip. But he said passengers either slid or were thrown to one side of the boat after it began lurching.

"And that, of course, would automatically mean an even bigger shift of weight," Bennett said. Earlier in the day, Bennett said the seats were not secured to deck. But later, state police said that was incorrect.

The captain of the 40-foot glass-enclosed boat told authorities it was hit by waves from at least one other vessel and turned over as he tried to steer out of them, authorities said earlier Monday. The boat flipped so fast that none of the 47 passengers — all senior citizens, most of them from Michigan — could put on a life jacket.

New York state regulations require that life jackets be made available for every person on a boat, but people do not have to wear them.

There was no immediate confirmation that another boat that could have churned up waves was in the area, and survivors were giving investigators differing versions of what happened before the boat went down in calm, sunny weather, authorities said.

Eight people were hospitalized with shortness of breath, broken bones and other injuries.

On Monday afternoon, crews using inflatable bags raised the sunken vessel 70 feet to the surface. They planned to pump it out and tow it to shore. National Transportation Safety Board investigators will then examine the wreck.

Mark Rosenker, NTSB acting chairman, said investigators would focus on such things as the history of the boat, the pilot's record, whether the boat had enough crew members, and whether the number of passengers played a role in the accident.

"It's much too early to determine what happened out on that lake," Rosenker said.

Rep. John Sweeney, R.-N.Y., said investigators are looking at whether there was too much weight on board the boat, even though the vessel was just below its capacity of 50 people. He said the Coast Guard assumes a weight of 150 pounds per person in calculating a vessel's capacity — an assumption he said may have been off the mark.

A survivor, 76-year-old old Jeane Siler of Trenton, Mich., said that she saw a wake coming and that the boat turned into it. She said she stood up and was either thrown or jumped into the water, where she found herself surrounded by other passengers. She suffered broken bones in her spine, a broken finger and bumps on her head.

Virgil Chambers, executive director of the National Safe Boating Council, an organization for recreational boaters, said investigators would probably examine how weight was distributed within the boat.

"If all the people were on one side, maybe to look at something, and if the operator were to take the boat over a wave at a particular angle, it could cause the boat to roll," Chambers said.

Chambers said he also expected investigators to look into whether there were any modifications to the craft, such as the addition of a canopy, that might have made the boat less stable.

The captain was not tested for drug or alcohol after the accident. The sheriff said he had no legal grounds for administering such a test. Also, the sheriff said Paris had a state license, rather than a Coast Guard one, which would have required a test for drugs or alcohol.

The boat was last inspected in May and no problems were found, state officials said.

Hundreds of boats were on the long, narrow lake about 50 miles north of Albany in the Adirondack Mountains, on the sunny Sunday afternoon, causing "a lot of wave action," Cleveland said.

When the Ethan Allen went over, people from nearby boats converged to try to rescue victims. Witnesses described a chaotic scene as the older victims, some of whom relied on walkers, cried out.

"The boat was sideways in the water, and people were screaming," said Joanne Rahal, who was in a boat when the Ethan Allen flipped. "Bodies were floating by our boat."

"We were just cruising along, and all of a sudden, the boat tipped. We thought it was kind of like a joke," Ann Mae Hawley, 74, told the Glens Falls Post-Star. "Next thing I knew, I was in the water under the boat. I could see my husband, and I called to him, but he didn't respond. I don't know where he is now."

A former captain of the boat, William Huus, said the Ethan Allen would list to the left when fully loaded because of the way the seats were configured. But he said he never had a problem with the boat. "I carried hours and hours and hours on that boat and she was, I thought, a very safe boat," Huus said.

A woman who answered the door at Paris' house and identified herself as the captain's wife said he was out of the house and would have no comment.

Only Colorado, Indiana and New Hampshire require adults to wear life preservers when a boat is motion, said Melissa Savage of the National Conference of State Legislatures. No states have special laws governing boaters who are elderly or infirm.

The Lake George Park Association and the sheriff's department are responsible for enforcing safety on the lake, and may reconsider the rules governing crew size and life jacket use, particularly when elderly or infirm passengers are involved, said James Hood, a spokesman for the association.

"It seems like a logical question or at least something to review," Hood said.

The trip was arranged through Canadian-based Shoreline Tours, which did not immediately return a call for comment. A separate company, Shoreline Cruises, owns the boat. It issued a statement saying it was "deeply saddened by yesterday's tragedy."