This frame grab made from video released by CBS3 (KYW-TV) shows rescuers assisting a passenger that was aboard a sightseeing boat that was knocked over by an oncoming barge in the Delaware River Wednesday, July 7, 2010, in Philadelphia. (AP Photo/CBS3/KWY-TV)<br>
PHILADELPHIA -- Hope faded for finding two tour boat passengers alive Thursday, a day after the amphibious craft they were riding in was struck and sunk by a barge in the Delaware River, spilling them and other passengers into the murky waters, searchers said.
A search for the missing duck boat passengers resumed in the morning near Philadelphia's Penn's Landing, with boats searching the surface and using sonar, but conditions were too dangerous to send divers underwater Thursday.
Interviews with other passengers indicated the missing 16-year-old girl and 20-year-old man were members of a Hungarian tour group, officials said.
"We're still searching with some hope," Coast Guard Capt. Todd Gatlin said Thursday at a news conference. "Hopes are fading -- but with some hope that they've survived. They could be in the boat, they could be other places."
Visibility at the bottom of the river, where the boat was lying in about 50 feet of water, was nil, said Philadelphia police Lt. Andrew Napoli, speaking of his earlier dives.
"The vehicle is laying upright on its wheels," he said. "There could be bodies inside, we're not sure. ... With the currents being what they are, if it went down with bodies inside, the bodies could very well have been washed out of the vessel."
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 massive Ben Franklin Bridge connecting Philadelphia to New Jersey.
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.
Ten people were taken to a hospital; two declined treatment, and eight were treated and released, Hahnemann University Hospital spokeswoman Coleen Cannon said.
The tour company, Norcross, Ga.-based Ride the Ducks, said Thursday that it was suspending operations nationwide, a day after it suspended its Philadelphia tours. It also operates tours in San Francisco, Seattle, Atlanta, Newport, R.I., and Branson, Mo.
"Our thoughts and prayers are with our Philadelphia guests, crew members and their families," the company said in a statement.
Associated Press writers Maryclaire Dale, JoAnn Loviglio, Kathy Matheson, Peter Jackson and Ron Todt contributed to this report.