LAKE GEORGE, N.Y. — 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 yesterday.

The Ethan Allen, which overturned Sunday on Lake George 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.

"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 yesterday, 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.

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 yesterday. 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.

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

Yesterday 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.

New York state has records on the vessel going back to 1983, and there has never been a problem with it, Gibson said. The boat was last inspected in May, state officials said.

Paris, a retired state trooper, has been licensed to operate the boat since 1986. He was not tested for drugs or alcohol after the accident; the sheriff said he had no grounds for giving such a test.

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.

Rep. John Sweeney, R.-N.Y., said investigators are looking at whether there was too much weight onboard the boat, even though the vessel was 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.

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."

One 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.

"We were just cruising along, and all of a sudden, the boat tipped. We thought it was kind of like a joke," survivor 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."

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."