PHILADELPHIA — Coast Guard officials say hope is fading for finding two missing tour boat passengers alive a day after the amphibious craft they were riding in was struck and sunk by a barge in the Delaware River.

Capt. Todd Gatlin said the search for the missing duck boat passengers resumed this morning near Philadelphia's Penn's Landing.

Officials said interviews with other passengers indicated the missing 16-year-old girl and 20-year-old man were members of a Hungarian tour group.

Divers located the sunken boat, but Gatlin said they will not dive back down to the vessel today because the murky water severely limits visibility.

Rescuers said 35 people were accounted for after the collision. A Coast Guard vessel was on scene overnight, and more boats resumed searching early today.

The 37 people aboard the six-wheeled duck boat were tossed overboard when the tugboat-pushed barge hit it after it had been adrift for a few minutes with its engine stalled, police said. Most were plucked from the river by other vessels in a frantic rescue operation that happened in full view of Penn's Landing, just south of the Ben Franklin Bridge.

The duck boat, which can travel seamlessly on land and water, had driven into the river Wednesday afternoon and suffered a mechanical problem and a small fire, officials said. It was struck about 10 minutes later by a barge used to transport sludge and sank to the bottom of the river.

Ten people were taken to a hospital; two declined treatment, and the other eight were treated and released, Hahnemann University Hospital spokeswoman Coleen Cannon said.

The National Transportation Safety Board said it planned to try to obtain any radio recordings, any possible mayday calls, photographs from witnesses or people aboard, and other evidence as its investigators remain in Philadelphia over the next several days.

NTSB member Robert Sumwalt said investigators would try to figure out why the vessels collided and "how conspicuous would that duck have been" to the tugboat pushing the 250-foot-long barge. NTSB officials also hoped to conduct witness interviews, he said.