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 regulators to suspend licenses for all five vessels belonging to the company that operated the tour, officials said Monday.

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.

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

“If that’s the case, there’s going to be a problem,” Warren County Sheriff Larry Cleveland said.

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.

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.